| Step | Hyp | Ref | Expression | 
						
							| 1 |  | breq1 | ⊢ ( 𝑎  =  𝐴  →  ( 𝑎 Range 𝑏  ↔  𝐴 Range 𝑏 ) ) | 
						
							| 2 |  | rneq | ⊢ ( 𝑎  =  𝐴  →  ran  𝑎  =  ran  𝐴 ) | 
						
							| 3 | 2 | eqeq2d | ⊢ ( 𝑎  =  𝐴  →  ( 𝑏  =  ran  𝑎  ↔  𝑏  =  ran  𝐴 ) ) | 
						
							| 4 | 1 3 | bibi12d | ⊢ ( 𝑎  =  𝐴  →  ( ( 𝑎 Range 𝑏  ↔  𝑏  =  ran  𝑎 )  ↔  ( 𝐴 Range 𝑏  ↔  𝑏  =  ran  𝐴 ) ) ) | 
						
							| 5 |  | breq2 | ⊢ ( 𝑏  =  𝐵  →  ( 𝐴 Range 𝑏  ↔  𝐴 Range 𝐵 ) ) | 
						
							| 6 |  | eqeq1 | ⊢ ( 𝑏  =  𝐵  →  ( 𝑏  =  ran  𝐴  ↔  𝐵  =  ran  𝐴 ) ) | 
						
							| 7 | 5 6 | bibi12d | ⊢ ( 𝑏  =  𝐵  →  ( ( 𝐴 Range 𝑏  ↔  𝑏  =  ran  𝐴 )  ↔  ( 𝐴 Range 𝐵  ↔  𝐵  =  ran  𝐴 ) ) ) | 
						
							| 8 |  | vex | ⊢ 𝑎  ∈  V | 
						
							| 9 |  | vex | ⊢ 𝑏  ∈  V | 
						
							| 10 | 8 9 | brrange | ⊢ ( 𝑎 Range 𝑏  ↔  𝑏  =  ran  𝑎 ) | 
						
							| 11 | 4 7 10 | vtocl2g | ⊢ ( ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑊 )  →  ( 𝐴 Range 𝐵  ↔  𝐵  =  ran  𝐴 ) ) |