| Step | Hyp | Ref | Expression | 
						
							| 1 |  | rng2idlring.r | ⊢ ( 𝜑  →  𝑅  ∈  Rng ) | 
						
							| 2 |  | rng2idlring.i | ⊢ ( 𝜑  →  𝐼  ∈  ( 2Ideal ‘ 𝑅 ) ) | 
						
							| 3 |  | rng2idlring.j | ⊢ 𝐽  =  ( 𝑅  ↾s  𝐼 ) | 
						
							| 4 |  | rng2idlring.u | ⊢ ( 𝜑  →  𝐽  ∈  Ring ) | 
						
							| 5 |  | rng2idlring.b | ⊢ 𝐵  =  ( Base ‘ 𝑅 ) | 
						
							| 6 |  | rng2idlring.t | ⊢  ·   =  ( .r ‘ 𝑅 ) | 
						
							| 7 |  | rng2idlring.1 | ⊢  1   =  ( 1r ‘ 𝐽 ) | 
						
							| 8 | 1 2 3 4 5 6 7 | rngqiprng1elbas | ⊢ ( 𝜑  →   1   ∈  𝐵 ) | 
						
							| 9 | 8 | anim1i | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝐵  ∧  𝐶  ∈  𝐵 ) )  →  (  1   ∈  𝐵  ∧  ( 𝐴  ∈  𝐵  ∧  𝐶  ∈  𝐵 ) ) ) | 
						
							| 10 |  | 3anass | ⊢ ( (  1   ∈  𝐵  ∧  𝐴  ∈  𝐵  ∧  𝐶  ∈  𝐵 )  ↔  (  1   ∈  𝐵  ∧  ( 𝐴  ∈  𝐵  ∧  𝐶  ∈  𝐵 ) ) ) | 
						
							| 11 | 9 10 | sylibr | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝐵  ∧  𝐶  ∈  𝐵 ) )  →  (  1   ∈  𝐵  ∧  𝐴  ∈  𝐵  ∧  𝐶  ∈  𝐵 ) ) | 
						
							| 12 |  | eqid | ⊢ ( +g ‘ 𝑅 )  =  ( +g ‘ 𝑅 ) | 
						
							| 13 | 5 12 6 | rngdi | ⊢ ( ( 𝑅  ∈  Rng  ∧  (  1   ∈  𝐵  ∧  𝐴  ∈  𝐵  ∧  𝐶  ∈  𝐵 ) )  →  (  1   ·  ( 𝐴 ( +g ‘ 𝑅 ) 𝐶 ) )  =  ( (  1   ·  𝐴 ) ( +g ‘ 𝑅 ) (  1   ·  𝐶 ) ) ) | 
						
							| 14 | 1 11 13 | syl2an2r | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝐵  ∧  𝐶  ∈  𝐵 ) )  →  (  1   ·  ( 𝐴 ( +g ‘ 𝑅 ) 𝐶 ) )  =  ( (  1   ·  𝐴 ) ( +g ‘ 𝑅 ) (  1   ·  𝐶 ) ) ) | 
						
							| 15 | 3 12 | ressplusg | ⊢ ( 𝐼  ∈  ( 2Ideal ‘ 𝑅 )  →  ( +g ‘ 𝑅 )  =  ( +g ‘ 𝐽 ) ) | 
						
							| 16 | 2 15 | syl | ⊢ ( 𝜑  →  ( +g ‘ 𝑅 )  =  ( +g ‘ 𝐽 ) ) | 
						
							| 17 | 16 | oveqd | ⊢ ( 𝜑  →  ( (  1   ·  𝐴 ) ( +g ‘ 𝑅 ) (  1   ·  𝐶 ) )  =  ( (  1   ·  𝐴 ) ( +g ‘ 𝐽 ) (  1   ·  𝐶 ) ) ) | 
						
							| 18 | 17 | adantr | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝐵  ∧  𝐶  ∈  𝐵 ) )  →  ( (  1   ·  𝐴 ) ( +g ‘ 𝑅 ) (  1   ·  𝐶 ) )  =  ( (  1   ·  𝐴 ) ( +g ‘ 𝐽 ) (  1   ·  𝐶 ) ) ) | 
						
							| 19 | 14 18 | eqtrd | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝐵  ∧  𝐶  ∈  𝐵 ) )  →  (  1   ·  ( 𝐴 ( +g ‘ 𝑅 ) 𝐶 ) )  =  ( (  1   ·  𝐴 ) ( +g ‘ 𝐽 ) (  1   ·  𝐶 ) ) ) |