| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mulgass3.b | ⊢ 𝐵  =  ( Base ‘ 𝑅 ) | 
						
							| 2 |  | mulgass3.m | ⊢  ·   =  ( .g ‘ 𝑅 ) | 
						
							| 3 |  | mulgass3.t | ⊢  ×   =  ( .r ‘ 𝑅 ) | 
						
							| 4 |  | eqid | ⊢ ( oppr ‘ 𝑅 )  =  ( oppr ‘ 𝑅 ) | 
						
							| 5 | 4 | opprring | ⊢ ( 𝑅  ∈  Ring  →  ( oppr ‘ 𝑅 )  ∈  Ring ) | 
						
							| 6 | 5 | adantr | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( oppr ‘ 𝑅 )  ∈  Ring ) | 
						
							| 7 |  | simpr1 | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  𝑁  ∈  ℤ ) | 
						
							| 8 |  | simpr3 | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  𝑌  ∈  𝐵 ) | 
						
							| 9 |  | simpr2 | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  𝑋  ∈  𝐵 ) | 
						
							| 10 | 4 1 | opprbas | ⊢ 𝐵  =  ( Base ‘ ( oppr ‘ 𝑅 ) ) | 
						
							| 11 |  | eqid | ⊢ ( .g ‘ ( oppr ‘ 𝑅 ) )  =  ( .g ‘ ( oppr ‘ 𝑅 ) ) | 
						
							| 12 |  | eqid | ⊢ ( .r ‘ ( oppr ‘ 𝑅 ) )  =  ( .r ‘ ( oppr ‘ 𝑅 ) ) | 
						
							| 13 | 10 11 12 | mulgass2 | ⊢ ( ( ( oppr ‘ 𝑅 )  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑌  ∈  𝐵  ∧  𝑋  ∈  𝐵 ) )  →  ( ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) 𝑌 ) ( .r ‘ ( oppr ‘ 𝑅 ) ) 𝑋 )  =  ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) ( 𝑌 ( .r ‘ ( oppr ‘ 𝑅 ) ) 𝑋 ) ) ) | 
						
							| 14 | 6 7 8 9 13 | syl13anc | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) 𝑌 ) ( .r ‘ ( oppr ‘ 𝑅 ) ) 𝑋 )  =  ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) ( 𝑌 ( .r ‘ ( oppr ‘ 𝑅 ) ) 𝑋 ) ) ) | 
						
							| 15 | 1 3 4 12 | opprmul | ⊢ ( ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) 𝑌 ) ( .r ‘ ( oppr ‘ 𝑅 ) ) 𝑋 )  =  ( 𝑋  ×  ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) 𝑌 ) ) | 
						
							| 16 | 1 3 4 12 | opprmul | ⊢ ( 𝑌 ( .r ‘ ( oppr ‘ 𝑅 ) ) 𝑋 )  =  ( 𝑋  ×  𝑌 ) | 
						
							| 17 | 16 | oveq2i | ⊢ ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) ( 𝑌 ( .r ‘ ( oppr ‘ 𝑅 ) ) 𝑋 ) )  =  ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) ( 𝑋  ×  𝑌 ) ) | 
						
							| 18 | 14 15 17 | 3eqtr3g | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑋  ×  ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) 𝑌 ) )  =  ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) ( 𝑋  ×  𝑌 ) ) ) | 
						
							| 19 | 1 | a1i | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  𝐵  =  ( Base ‘ 𝑅 ) ) | 
						
							| 20 | 10 | a1i | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  𝐵  =  ( Base ‘ ( oppr ‘ 𝑅 ) ) ) | 
						
							| 21 |  | ssv | ⊢ 𝐵  ⊆  V | 
						
							| 22 | 21 | a1i | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  𝐵  ⊆  V ) | 
						
							| 23 |  | ovexd | ⊢ ( ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  ∧  ( 𝑥  ∈  V  ∧  𝑦  ∈  V ) )  →  ( 𝑥 ( +g ‘ 𝑅 ) 𝑦 )  ∈  V ) | 
						
							| 24 |  | eqid | ⊢ ( +g ‘ 𝑅 )  =  ( +g ‘ 𝑅 ) | 
						
							| 25 | 4 24 | oppradd | ⊢ ( +g ‘ 𝑅 )  =  ( +g ‘ ( oppr ‘ 𝑅 ) ) | 
						
							| 26 | 25 | oveqi | ⊢ ( 𝑥 ( +g ‘ 𝑅 ) 𝑦 )  =  ( 𝑥 ( +g ‘ ( oppr ‘ 𝑅 ) ) 𝑦 ) | 
						
							| 27 | 26 | a1i | ⊢ ( ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  ∧  ( 𝑥  ∈  V  ∧  𝑦  ∈  V ) )  →  ( 𝑥 ( +g ‘ 𝑅 ) 𝑦 )  =  ( 𝑥 ( +g ‘ ( oppr ‘ 𝑅 ) ) 𝑦 ) ) | 
						
							| 28 | 2 11 19 20 22 23 27 | mulgpropd | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →   ·   =  ( .g ‘ ( oppr ‘ 𝑅 ) ) ) | 
						
							| 29 | 28 | oveqd | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑁  ·  𝑌 )  =  ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) 𝑌 ) ) | 
						
							| 30 | 29 | oveq2d | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑋  ×  ( 𝑁  ·  𝑌 ) )  =  ( 𝑋  ×  ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) 𝑌 ) ) ) | 
						
							| 31 | 28 | oveqd | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑁  ·  ( 𝑋  ×  𝑌 ) )  =  ( 𝑁 ( .g ‘ ( oppr ‘ 𝑅 ) ) ( 𝑋  ×  𝑌 ) ) ) | 
						
							| 32 | 18 30 31 | 3eqtr4d | ⊢ ( ( 𝑅  ∈  Ring  ∧  ( 𝑁  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑋  ×  ( 𝑁  ·  𝑌 ) )  =  ( 𝑁  ·  ( 𝑋  ×  𝑌 ) ) ) |