| Step | Hyp | Ref | Expression | 
						
							| 1 |  | sbcan | ⊢ ( [ 𝐴  /  𝑥 ] ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 )  ↔  ( [ 𝐴  /  𝑥 ] ( 𝜑  ∧  𝜓 )  ∧  [ 𝐴  /  𝑥 ] 𝜒 ) ) | 
						
							| 2 |  | sbcan | ⊢ ( [ 𝐴  /  𝑥 ] ( 𝜑  ∧  𝜓 )  ↔  ( [ 𝐴  /  𝑥 ] 𝜑  ∧  [ 𝐴  /  𝑥 ] 𝜓 ) ) | 
						
							| 3 | 1 2 | bianbi | ⊢ ( [ 𝐴  /  𝑥 ] ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 )  ↔  ( ( [ 𝐴  /  𝑥 ] 𝜑  ∧  [ 𝐴  /  𝑥 ] 𝜓 )  ∧  [ 𝐴  /  𝑥 ] 𝜒 ) ) | 
						
							| 4 |  | df-3an | ⊢ ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  ↔  ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 ) ) | 
						
							| 5 | 4 | sbcbii | ⊢ ( [ 𝐴  /  𝑥 ] ( 𝜑  ∧  𝜓  ∧  𝜒 )  ↔  [ 𝐴  /  𝑥 ] ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 ) ) | 
						
							| 6 |  | df-3an | ⊢ ( ( [ 𝐴  /  𝑥 ] 𝜑  ∧  [ 𝐴  /  𝑥 ] 𝜓  ∧  [ 𝐴  /  𝑥 ] 𝜒 )  ↔  ( ( [ 𝐴  /  𝑥 ] 𝜑  ∧  [ 𝐴  /  𝑥 ] 𝜓 )  ∧  [ 𝐴  /  𝑥 ] 𝜒 ) ) | 
						
							| 7 | 3 5 6 | 3bitr4i | ⊢ ( [ 𝐴  /  𝑥 ] ( 𝜑  ∧  𝜓  ∧  𝜒 )  ↔  ( [ 𝐴  /  𝑥 ] 𝜑  ∧  [ 𝐴  /  𝑥 ] 𝜓  ∧  [ 𝐴  /  𝑥 ] 𝜒 ) ) |