| Step | Hyp | Ref | Expression | 
						
							| 1 |  | xp1st | ⊢ ( 𝐴  ∈  ( N  ×  N )  →  ( 1st  ‘ 𝐴 )  ∈  N ) | 
						
							| 2 | 1 | 3ad2ant1 | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 1st  ‘ 𝐴 )  ∈  N ) | 
						
							| 3 |  | xp2nd | ⊢ ( 𝐶  ∈  ( N  ×  N )  →  ( 2nd  ‘ 𝐶 )  ∈  N ) | 
						
							| 4 | 3 | 3ad2ant3 | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 2nd  ‘ 𝐶 )  ∈  N ) | 
						
							| 5 |  | mulclpi | ⊢ ( ( ( 1st  ‘ 𝐴 )  ∈  N  ∧  ( 2nd  ‘ 𝐶 )  ∈  N )  →  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N ) | 
						
							| 6 | 2 4 5 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N ) | 
						
							| 7 |  | xp1st | ⊢ ( 𝐶  ∈  ( N  ×  N )  →  ( 1st  ‘ 𝐶 )  ∈  N ) | 
						
							| 8 | 7 | 3ad2ant3 | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 1st  ‘ 𝐶 )  ∈  N ) | 
						
							| 9 |  | xp2nd | ⊢ ( 𝐴  ∈  ( N  ×  N )  →  ( 2nd  ‘ 𝐴 )  ∈  N ) | 
						
							| 10 | 9 | 3ad2ant1 | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 2nd  ‘ 𝐴 )  ∈  N ) | 
						
							| 11 |  | mulclpi | ⊢ ( ( ( 1st  ‘ 𝐶 )  ∈  N  ∧  ( 2nd  ‘ 𝐴 )  ∈  N )  →  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) )  ∈  N ) | 
						
							| 12 | 8 10 11 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) )  ∈  N ) | 
						
							| 13 |  | addclpi | ⊢ ( ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N  ∧  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) )  ∈  N )  →  ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ∈  N ) | 
						
							| 14 | 6 12 13 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ∈  N ) | 
						
							| 15 |  | mulclpi | ⊢ ( ( ( 2nd  ‘ 𝐴 )  ∈  N  ∧  ( 2nd  ‘ 𝐶 )  ∈  N )  →  ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N ) | 
						
							| 16 | 10 4 15 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N ) | 
						
							| 17 |  | xp1st | ⊢ ( 𝐵  ∈  ( N  ×  N )  →  ( 1st  ‘ 𝐵 )  ∈  N ) | 
						
							| 18 | 17 | 3ad2ant2 | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 1st  ‘ 𝐵 )  ∈  N ) | 
						
							| 19 |  | mulclpi | ⊢ ( ( ( 1st  ‘ 𝐵 )  ∈  N  ∧  ( 2nd  ‘ 𝐶 )  ∈  N )  →  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N ) | 
						
							| 20 | 18 4 19 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N ) | 
						
							| 21 |  | xp2nd | ⊢ ( 𝐵  ∈  ( N  ×  N )  →  ( 2nd  ‘ 𝐵 )  ∈  N ) | 
						
							| 22 | 21 | 3ad2ant2 | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 2nd  ‘ 𝐵 )  ∈  N ) | 
						
							| 23 |  | mulclpi | ⊢ ( ( ( 1st  ‘ 𝐶 )  ∈  N  ∧  ( 2nd  ‘ 𝐵 )  ∈  N )  →  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) )  ∈  N ) | 
						
							| 24 | 8 22 23 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) )  ∈  N ) | 
						
							| 25 |  | addclpi | ⊢ ( ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N  ∧  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) )  ∈  N )  →  ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  ∈  N ) | 
						
							| 26 | 20 24 25 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  ∈  N ) | 
						
							| 27 |  | mulclpi | ⊢ ( ( ( 2nd  ‘ 𝐵 )  ∈  N  ∧  ( 2nd  ‘ 𝐶 )  ∈  N )  →  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N ) | 
						
							| 28 | 22 4 27 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N ) | 
						
							| 29 |  | enqbreq | ⊢ ( ( ( ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ∈  N  ∧  ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N )  ∧  ( ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  ∈  N  ∧  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N ) )  →  ( 〈 ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) ,  ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) ) 〉  ~Q  〈 ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ,  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) 〉  ↔  ( ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) )  =  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ) ) ) | 
						
							| 30 | 14 16 26 28 29 | syl22anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 〈 ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) ,  ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) ) 〉  ~Q  〈 ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ,  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) 〉  ↔  ( ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) )  =  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ) ) ) | 
						
							| 31 |  | addpipq2 | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 𝐴  +pQ  𝐶 )  =  〈 ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) ,  ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) ) 〉 ) | 
						
							| 32 | 31 | 3adant2 | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 𝐴  +pQ  𝐶 )  =  〈 ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) ,  ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) ) 〉 ) | 
						
							| 33 |  | addpipq2 | ⊢ ( ( 𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 𝐵  +pQ  𝐶 )  =  〈 ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ,  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) 〉 ) | 
						
							| 34 | 33 | 3adant1 | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 𝐵  +pQ  𝐶 )  =  〈 ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ,  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) 〉 ) | 
						
							| 35 | 32 34 | breq12d | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( 𝐴  +pQ  𝐶 )  ~Q  ( 𝐵  +pQ  𝐶 )  ↔  〈 ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) ,  ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) ) 〉  ~Q  〈 ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ,  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) 〉 ) ) | 
						
							| 36 |  | enqbreq2 | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N ) )  →  ( 𝐴  ~Q  𝐵  ↔  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) )  =  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) ) | 
						
							| 37 | 36 | 3adant3 | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 𝐴  ~Q  𝐵  ↔  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) )  =  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) ) | 
						
							| 38 |  | mulclpi | ⊢ ( ( ( 2nd  ‘ 𝐶 )  ∈  N  ∧  ( 2nd  ‘ 𝐶 )  ∈  N )  →  ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N ) | 
						
							| 39 | 4 4 38 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N ) | 
						
							| 40 |  | mulclpi | ⊢ ( ( ( 1st  ‘ 𝐴 )  ∈  N  ∧  ( 2nd  ‘ 𝐵 )  ∈  N )  →  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) )  ∈  N ) | 
						
							| 41 | 2 22 40 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) )  ∈  N ) | 
						
							| 42 |  | mulcanpi | ⊢ ( ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N  ∧  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) )  ∈  N )  →  ( ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  =  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ↔  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) )  =  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) ) | 
						
							| 43 | 39 41 42 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  =  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ↔  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) )  =  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) ) | 
						
							| 44 |  | mulclpi | ⊢ ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N  ∧  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) )  ∈  N )  →  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  ∈  N ) | 
						
							| 45 | 16 24 44 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  ∈  N ) | 
						
							| 46 |  | mulclpi | ⊢ ( ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  N  ∧  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) )  ∈  N )  →  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  ∈  N ) | 
						
							| 47 | 39 41 46 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  ∈  N ) | 
						
							| 48 |  | addcanpi | ⊢ ( ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  ∈  N  ∧  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  ∈  N )  →  ( ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) )  =  ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) )  ↔  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  =  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) ) ) | 
						
							| 49 | 45 47 48 | syl2anc | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) )  =  ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) )  ↔  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  =  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) ) ) | 
						
							| 50 |  | mulcompi | ⊢ ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  =  ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) )  ·N  ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) | 
						
							| 51 |  | fvex | ⊢ ( 1st  ‘ 𝐴 )  ∈  V | 
						
							| 52 |  | fvex | ⊢ ( 2nd  ‘ 𝐵 )  ∈  V | 
						
							| 53 |  | fvex | ⊢ ( 2nd  ‘ 𝐶 )  ∈  V | 
						
							| 54 |  | mulcompi | ⊢ ( 𝑥  ·N  𝑦 )  =  ( 𝑦  ·N  𝑥 ) | 
						
							| 55 |  | mulasspi | ⊢ ( ( 𝑥  ·N  𝑦 )  ·N  𝑧 )  =  ( 𝑥  ·N  ( 𝑦  ·N  𝑧 ) ) | 
						
							| 56 | 51 52 53 54 55 53 | caov4 | ⊢ ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) )  ·N  ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) ) )  =  ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) | 
						
							| 57 | 50 56 | eqtri | ⊢ ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  =  ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) | 
						
							| 58 |  | fvex | ⊢ ( 2nd  ‘ 𝐴 )  ∈  V | 
						
							| 59 |  | fvex | ⊢ ( 1st  ‘ 𝐶 )  ∈  V | 
						
							| 60 | 58 53 59 54 55 52 | caov4 | ⊢ ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  =  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 1st  ‘ 𝐶 ) )  ·N  ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) | 
						
							| 61 |  | mulcompi | ⊢ ( ( 2nd  ‘ 𝐴 )  ·N  ( 1st  ‘ 𝐶 ) )  =  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) | 
						
							| 62 |  | mulcompi | ⊢ ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) )  =  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) | 
						
							| 63 | 61 62 | oveq12i | ⊢ ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 1st  ‘ 𝐶 ) )  ·N  ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  =  ( ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) | 
						
							| 64 | 60 63 | eqtri | ⊢ ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  =  ( ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) | 
						
							| 65 | 57 64 | oveq12i | ⊢ ( ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) )  =  ( ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) )  +N  ( ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) ) | 
						
							| 66 |  | addcompi | ⊢ ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) )  =  ( ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ) | 
						
							| 67 |  | ovex | ⊢ ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  V | 
						
							| 68 |  | ovex | ⊢ ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) )  ∈  V | 
						
							| 69 |  | ovex | ⊢ ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  ∈  V | 
						
							| 70 |  | distrpi | ⊢ ( 𝑥  ·N  ( 𝑦  +N  𝑧 ) )  =  ( ( 𝑥  ·N  𝑦 )  +N  ( 𝑥  ·N  𝑧 ) ) | 
						
							| 71 | 67 68 69 54 70 | caovdir | ⊢ ( ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) )  =  ( ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) )  +N  ( ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) ) | 
						
							| 72 | 65 66 71 | 3eqtr4i | ⊢ ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) )  =  ( ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) | 
						
							| 73 |  | addcompi | ⊢ ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) )  =  ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) )  +N  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ) | 
						
							| 74 |  | mulasspi | ⊢ ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  =  ( ( 2nd  ‘ 𝐶 )  ·N  ( ( 2nd  ‘ 𝐶 )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) ) | 
						
							| 75 |  | mulcompi | ⊢ ( ( 2nd  ‘ 𝐶 )  ·N  ( ( 2nd  ‘ 𝐶 )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) )  =  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ·N  ( 2nd  ‘ 𝐶 ) ) | 
						
							| 76 |  | mulasspi | ⊢ ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( 1st  ‘ 𝐵 ) )  =  ( ( 2nd  ‘ 𝐴 )  ·N  ( ( 2nd  ‘ 𝐶 )  ·N  ( 1st  ‘ 𝐵 ) ) ) | 
						
							| 77 |  | mulcompi | ⊢ ( ( 2nd  ‘ 𝐴 )  ·N  ( ( 2nd  ‘ 𝐶 )  ·N  ( 1st  ‘ 𝐵 ) ) )  =  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 1st  ‘ 𝐵 ) )  ·N  ( 2nd  ‘ 𝐴 ) ) | 
						
							| 78 |  | mulasspi | ⊢ ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 1st  ‘ 𝐵 ) )  ·N  ( 2nd  ‘ 𝐴 ) )  =  ( ( 2nd  ‘ 𝐶 )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) | 
						
							| 79 | 76 77 78 | 3eqtrri | ⊢ ( ( 2nd  ‘ 𝐶 )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  =  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( 1st  ‘ 𝐵 ) ) | 
						
							| 80 | 79 | oveq1i | ⊢ ( ( ( 2nd  ‘ 𝐶 )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ·N  ( 2nd  ‘ 𝐶 ) )  =  ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( 1st  ‘ 𝐵 ) )  ·N  ( 2nd  ‘ 𝐶 ) ) | 
						
							| 81 | 75 80 | eqtri | ⊢ ( ( 2nd  ‘ 𝐶 )  ·N  ( ( 2nd  ‘ 𝐶 )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) )  =  ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( 1st  ‘ 𝐵 ) )  ·N  ( 2nd  ‘ 𝐶 ) ) | 
						
							| 82 |  | mulasspi | ⊢ ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( 1st  ‘ 𝐵 ) )  ·N  ( 2nd  ‘ 𝐶 ) )  =  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) | 
						
							| 83 | 81 82 | eqtri | ⊢ ( ( 2nd  ‘ 𝐶 )  ·N  ( ( 2nd  ‘ 𝐶 )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) )  =  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) | 
						
							| 84 | 74 83 | eqtri | ⊢ ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  =  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) | 
						
							| 85 | 84 | oveq2i | ⊢ ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) )  =  ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) ) ) | 
						
							| 86 |  | distrpi | ⊢ ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) )  =  ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) )  +N  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ) | 
						
							| 87 | 73 85 86 | 3eqtr4i | ⊢ ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) )  =  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ) | 
						
							| 88 | 72 87 | eqeq12i | ⊢ ( ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) )  =  ( ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  +N  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) ) )  ↔  ( ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) )  =  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ) ) | 
						
							| 89 | 49 88 | bitr3di | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐵 ) ) )  =  ( ( ( 2nd  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ↔  ( ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) )  =  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ) ) ) | 
						
							| 90 | 37 43 89 | 3bitr2d | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 𝐴  ~Q  𝐵  ↔  ( ( ( ( 1st  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐴 ) ) )  ·N  ( ( 2nd  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) ) )  =  ( ( ( 2nd  ‘ 𝐴 )  ·N  ( 2nd  ‘ 𝐶 ) )  ·N  ( ( ( 1st  ‘ 𝐵 )  ·N  ( 2nd  ‘ 𝐶 ) )  +N  ( ( 1st  ‘ 𝐶 )  ·N  ( 2nd  ‘ 𝐵 ) ) ) ) ) ) | 
						
							| 91 | 30 35 90 | 3bitr4rd | ⊢ ( ( 𝐴  ∈  ( N  ×  N )  ∧  𝐵  ∈  ( N  ×  N )  ∧  𝐶  ∈  ( N  ×  N ) )  →  ( 𝐴  ~Q  𝐵  ↔  ( 𝐴  +pQ  𝐶 )  ~Q  ( 𝐵  +pQ  𝐶 ) ) ) |