| Step | Hyp | Ref | Expression | 
						
							| 1 |  | addsdilem.1 | ⊢ ( 𝜑  →  𝐴  ∈   No  ) | 
						
							| 2 |  | addsdilem.2 | ⊢ ( 𝜑  →  𝐵  ∈   No  ) | 
						
							| 3 |  | addsdilem.3 | ⊢ ( 𝜑  →  𝐶  ∈   No  ) | 
						
							| 4 | 1 2 | mulscut2 | ⊢ ( 𝜑  →  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } )  <<s  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } ) ) | 
						
							| 5 | 1 3 | mulscut2 | ⊢ ( 𝜑  →  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } )  <<s  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } ) ) | 
						
							| 6 |  | mulsval2 | ⊢ ( ( 𝐴  ∈   No   ∧  𝐵  ∈   No  )  →  ( 𝐴  ·s  𝐵 )  =  ( ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } )  |s  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } ) ) ) | 
						
							| 7 | 1 2 6 | syl2anc | ⊢ ( 𝜑  →  ( 𝐴  ·s  𝐵 )  =  ( ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } )  |s  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } ) ) ) | 
						
							| 8 |  | mulsval2 | ⊢ ( ( 𝐴  ∈   No   ∧  𝐶  ∈   No  )  →  ( 𝐴  ·s  𝐶 )  =  ( ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } )  |s  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } ) ) ) | 
						
							| 9 | 1 3 8 | syl2anc | ⊢ ( 𝜑  →  ( 𝐴  ·s  𝐶 )  =  ( ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } )  |s  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } ) ) ) | 
						
							| 10 | 4 5 7 9 | addsunif | ⊢ ( 𝜑  →  ( ( 𝐴  ·s  𝐵 )  +s  ( 𝐴  ·s  𝐶 ) )  =  ( ( { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) } )  |s  ( { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) } ) ) ) | 
						
							| 11 |  | unab | ⊢ ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) } )  =  { 𝑎  ∣  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) } | 
						
							| 12 |  | rexun | ⊢ ( ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ∨  ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 13 |  | eqeq1 | ⊢ ( 𝑏  =  𝑡  →  ( 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ↔  𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) ) ) | 
						
							| 14 | 13 | 2rexbidv | ⊢ ( 𝑏  =  𝑡  →  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) ) ) | 
						
							| 15 | 14 | rexab | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  ∃ 𝑡 ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 16 |  | rexcom4 | ⊢ ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡 ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 17 |  | rexcom4 | ⊢ ( ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡 ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 18 |  | ovex | ⊢ ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∈  V | 
						
							| 19 |  | oveq1 | ⊢ ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  →  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 20 | 19 | eqeq2d | ⊢ ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  →  ( 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 21 | 18 20 | ceqsexv | ⊢ ( ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 22 | 21 | rexbii | ⊢ ( ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 23 | 17 22 | bitr3i | ⊢ ( ∃ 𝑡 ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 24 | 23 | rexbii | ⊢ ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 25 |  | r19.41vv | ⊢ ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 26 | 25 | exbii | ⊢ ( ∃ 𝑡 ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡 ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 27 | 16 24 26 | 3bitr3ri | ⊢ ( ∃ 𝑡 ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 28 | 15 27 | bitri | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 29 |  | eqeq1 | ⊢ ( 𝑏  =  𝑡  →  ( 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ↔  𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) ) ) | 
						
							| 30 | 29 | 2rexbidv | ⊢ ( 𝑏  =  𝑡  →  ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) ) ) | 
						
							| 31 | 30 | rexab | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  ∃ 𝑡 ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 32 |  | rexcom4 | ⊢ ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡 ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 33 |  | rexcom4 | ⊢ ( ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡 ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 34 |  | ovex | ⊢ ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∈  V | 
						
							| 35 |  | oveq1 | ⊢ ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  →  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 36 | 35 | eqeq2d | ⊢ ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  →  ( 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 37 | 34 36 | ceqsexv | ⊢ ( ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 38 | 37 | rexbii | ⊢ ( ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 39 | 33 38 | bitr3i | ⊢ ( ∃ 𝑡 ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 40 | 39 | rexbii | ⊢ ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 41 |  | r19.41vv | ⊢ ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 42 | 41 | exbii | ⊢ ( ∃ 𝑡 ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡 ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 43 | 32 40 42 | 3bitr3ri | ⊢ ( ∃ 𝑡 ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 44 | 31 43 | bitri | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 45 | 28 44 | orbi12i | ⊢ ( ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ∨  ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 46 | 12 45 | bitr2i | ⊢ ( ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 47 | 46 | abbii | ⊢ { 𝑎  ∣  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) }  =  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) } | 
						
							| 48 | 11 47 | eqtri | ⊢ ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) } )  =  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) } | 
						
							| 49 |  | unab | ⊢ ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) } )  =  { 𝑎  ∣  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) } | 
						
							| 50 |  | rexun | ⊢ ( ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ∨  ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 51 |  | eqeq1 | ⊢ ( 𝑏  =  𝑡  →  ( 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ↔  𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 52 | 51 | 2rexbidv | ⊢ ( 𝑏  =  𝑡  →  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 53 | 52 | rexab | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  ∃ 𝑡 ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 54 |  | rexcom4 | ⊢ ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑡 ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 55 |  | rexcom4 | ⊢ ( ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑡 ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 56 |  | ovex | ⊢ ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∈  V | 
						
							| 57 |  | oveq2 | ⊢ ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  →  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 58 | 57 | eqeq2d | ⊢ ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  →  ( 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) ) ) | 
						
							| 59 | 56 58 | ceqsexv | ⊢ ( ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 60 | 59 | rexbii | ⊢ ( ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 61 | 55 60 | bitr3i | ⊢ ( ∃ 𝑡 ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 62 | 61 | rexbii | ⊢ ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 63 |  | r19.41vv | ⊢ ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 64 | 63 | exbii | ⊢ ( ∃ 𝑡 ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑡 ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 65 | 54 62 64 | 3bitr3ri | ⊢ ( ∃ 𝑡 ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 66 | 53 65 | bitri | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 67 |  | eqeq1 | ⊢ ( 𝑏  =  𝑡  →  ( 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ↔  𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 68 | 67 | 2rexbidv | ⊢ ( 𝑏  =  𝑡  →  ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 69 | 68 | rexab | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  ∃ 𝑡 ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 70 |  | rexcom4 | ⊢ ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑡 ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 71 |  | rexcom4 | ⊢ ( ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑡 ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 72 |  | ovex | ⊢ ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∈  V | 
						
							| 73 |  | oveq2 | ⊢ ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  →  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 74 | 73 | eqeq2d | ⊢ ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  →  ( 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) ) | 
						
							| 75 | 72 74 | ceqsexv | ⊢ ( ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 76 | 75 | rexbii | ⊢ ( ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 77 | 71 76 | bitr3i | ⊢ ( ∃ 𝑡 ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 78 | 77 | rexbii | ⊢ ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 79 |  | r19.41vv | ⊢ ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 80 | 79 | exbii | ⊢ ( ∃ 𝑡 ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑡 ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 81 | 70 78 80 | 3bitr3ri | ⊢ ( ∃ 𝑡 ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 82 | 69 81 | bitri | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 83 | 66 82 | orbi12i | ⊢ ( ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ∨  ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) ) | 
						
							| 84 | 50 83 | bitr2i | ⊢ ( ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) )  ↔  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) | 
						
							| 85 | 84 | abbii | ⊢ { 𝑎  ∣  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) ) }  =  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) } | 
						
							| 86 | 49 85 | eqtri | ⊢ ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) } )  =  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) } | 
						
							| 87 | 48 86 | uneq12i | ⊢ ( ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) } )  ∪  ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) } ) )  =  ( { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) } ) | 
						
							| 88 |  | unab | ⊢ ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) } )  =  { 𝑎  ∣  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) } | 
						
							| 89 |  | rexun | ⊢ ( ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ∨  ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 90 |  | eqeq1 | ⊢ ( 𝑏  =  𝑡  →  ( 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ↔  𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) ) ) | 
						
							| 91 | 90 | 2rexbidv | ⊢ ( 𝑏  =  𝑡  →  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) ) ) | 
						
							| 92 | 91 | rexab | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  ∃ 𝑡 ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 93 |  | rexcom4 | ⊢ ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡 ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 94 |  | rexcom4 | ⊢ ( ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡 ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 95 |  | ovex | ⊢ ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∈  V | 
						
							| 96 |  | oveq1 | ⊢ ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  →  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 97 | 96 | eqeq2d | ⊢ ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  →  ( 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 98 | 95 97 | ceqsexv | ⊢ ( ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 99 | 98 | rexbii | ⊢ ( ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 100 | 94 99 | bitr3i | ⊢ ( ∃ 𝑡 ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 101 | 100 | rexbii | ⊢ ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 102 |  | r19.41vv | ⊢ ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 103 | 102 | exbii | ⊢ ( ∃ 𝑡 ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡 ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 104 | 93 101 103 | 3bitr3ri | ⊢ ( ∃ 𝑡 ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 105 | 92 104 | bitri | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 106 |  | eqeq1 | ⊢ ( 𝑏  =  𝑡  →  ( 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ↔  𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) ) ) | 
						
							| 107 | 106 | 2rexbidv | ⊢ ( 𝑏  =  𝑡  →  ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) ) ) | 
						
							| 108 | 107 | rexab | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  ∃ 𝑡 ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 109 |  | rexcom4 | ⊢ ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡 ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 110 |  | rexcom4 | ⊢ ( ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡 ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 111 |  | ovex | ⊢ ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∈  V | 
						
							| 112 |  | oveq1 | ⊢ ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  →  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 113 | 112 | eqeq2d | ⊢ ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  →  ( 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 114 | 111 113 | ceqsexv | ⊢ ( ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 115 | 114 | rexbii | ⊢ ( ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 116 | 110 115 | bitr3i | ⊢ ( ∃ 𝑡 ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 117 | 116 | rexbii | ⊢ ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 118 |  | r19.41vv | ⊢ ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 119 | 118 | exbii | ⊢ ( ∃ 𝑡 ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡 ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 120 | 109 117 119 | 3bitr3ri | ⊢ ( ∃ 𝑡 ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  ∧  𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 121 | 108 120 | bitri | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 122 | 105 121 | orbi12i | ⊢ ( ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) )  ∨  ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) ) | 
						
							| 123 | 89 122 | bitr2i | ⊢ ( ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) )  ↔  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) ) | 
						
							| 124 | 123 | abbii | ⊢ { 𝑎  ∣  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) ) }  =  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) } | 
						
							| 125 | 88 124 | eqtri | ⊢ ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) } )  =  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) } | 
						
							| 126 |  | unab | ⊢ ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) } )  =  { 𝑎  ∣  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) } | 
						
							| 127 |  | rexun | ⊢ ( ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ∨  ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 128 |  | eqeq1 | ⊢ ( 𝑏  =  𝑡  →  ( 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ↔  𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 129 | 128 | 2rexbidv | ⊢ ( 𝑏  =  𝑡  →  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 130 | 129 | rexab | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  ∃ 𝑡 ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 131 |  | rexcom4 | ⊢ ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑡 ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 132 |  | rexcom4 | ⊢ ( ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑡 ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 133 |  | ovex | ⊢ ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∈  V | 
						
							| 134 |  | oveq2 | ⊢ ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  →  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 135 | 134 | eqeq2d | ⊢ ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  →  ( 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) ) ) | 
						
							| 136 | 133 135 | ceqsexv | ⊢ ( ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 137 | 136 | rexbii | ⊢ ( ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 138 | 132 137 | bitr3i | ⊢ ( ∃ 𝑡 ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 139 | 138 | rexbii | ⊢ ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 140 |  | r19.41vv | ⊢ ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 141 | 140 | exbii | ⊢ ( ∃ 𝑡 ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑡 ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 142 | 131 139 141 | 3bitr3ri | ⊢ ( ∃ 𝑡 ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 143 | 130 142 | bitri | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) ) | 
						
							| 144 |  | eqeq1 | ⊢ ( 𝑏  =  𝑡  →  ( 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ↔  𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 145 | 144 | 2rexbidv | ⊢ ( 𝑏  =  𝑡  →  ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 146 | 145 | rexab | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  ∃ 𝑡 ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 147 |  | rexcom4 | ⊢ ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑡 ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 148 |  | rexcom4 | ⊢ ( ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑡 ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 149 |  | ovex | ⊢ ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∈  V | 
						
							| 150 |  | oveq2 | ⊢ ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  →  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 151 | 150 | eqeq2d | ⊢ ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  →  ( 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) ) | 
						
							| 152 | 149 151 | ceqsexv | ⊢ ( ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 153 | 152 | rexbii | ⊢ ( ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ∃ 𝑡 ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 154 | 148 153 | bitr3i | ⊢ ( ∃ 𝑡 ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 155 | 154 | rexbii | ⊢ ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑡 ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 156 |  | r19.41vv | ⊢ ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 157 | 156 | exbii | ⊢ ( ∃ 𝑡 ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) ( 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑡 ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) ) | 
						
							| 158 | 147 155 157 | 3bitr3ri | ⊢ ( ∃ 𝑡 ( ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑡  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) )  ∧  𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 159 | 146 158 | bitri | ⊢ ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ↔  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) | 
						
							| 160 | 143 159 | orbi12i | ⊢ ( ( ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 )  ∨  ∃ 𝑡  ∈  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) )  ↔  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) ) | 
						
							| 161 | 127 160 | bitr2i | ⊢ ( ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) )  ↔  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) ) | 
						
							| 162 | 161 | abbii | ⊢ { 𝑎  ∣  ( ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) )  ∨  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) ) }  =  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) } | 
						
							| 163 | 126 162 | eqtri | ⊢ ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) } )  =  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) } | 
						
							| 164 | 125 163 | uneq12i | ⊢ ( ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) } )  ∪  ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) } ) )  =  ( { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) } ) | 
						
							| 165 | 87 164 | oveq12i | ⊢ ( ( ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) } )  ∪  ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) } ) )  |s  ( ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) } )  ∪  ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) } ) ) )  =  ( ( { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) } )  |s  ( { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) ) } ) 𝑎  =  ( 𝑡  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑡  ∈  ( { 𝑏  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) }  ∪  { 𝑏  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑏  =  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) } ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  𝑡 ) } ) ) | 
						
							| 166 | 10 165 | eqtr4di | ⊢ ( 𝜑  →  ( ( 𝐴  ·s  𝐵 )  +s  ( 𝐴  ·s  𝐶 ) )  =  ( ( ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) } )  ∪  ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝐿 ) ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝑅 ) ) ) } ) )  |s  ( ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑦𝑅  ∈  (  R  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝐿  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑦𝑅 ) )  +s  ( 𝐴  ·s  𝐶 ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑦𝐿  ∈  (  L  ‘ 𝐵 ) 𝑎  =  ( ( ( ( 𝑥𝑅  ·s  𝐵 )  +s  ( 𝐴  ·s  𝑦𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑦𝐿 ) )  +s  ( 𝐴  ·s  𝐶 ) ) } )  ∪  ( { 𝑎  ∣  ∃ 𝑥𝐿  ∈  (  L  ‘ 𝐴 ) ∃ 𝑧𝑅  ∈  (  R  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝐿  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝑅 ) )  -s  ( 𝑥𝐿  ·s  𝑧𝑅 ) ) ) }  ∪  { 𝑎  ∣  ∃ 𝑥𝑅  ∈  (  R  ‘ 𝐴 ) ∃ 𝑧𝐿  ∈  (  L  ‘ 𝐶 ) 𝑎  =  ( ( 𝐴  ·s  𝐵 )  +s  ( ( ( 𝑥𝑅  ·s  𝐶 )  +s  ( 𝐴  ·s  𝑧𝐿 ) )  -s  ( 𝑥𝑅  ·s  𝑧𝐿 ) ) ) } ) ) ) ) |