| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mulgass3.b |  |-  B = ( Base ` R ) | 
						
							| 2 |  | mulgass3.m |  |-  .x. = ( .g ` R ) | 
						
							| 3 |  | mulgass3.t |  |-  .X. = ( .r ` R ) | 
						
							| 4 |  | eqid |  |-  ( oppR ` R ) = ( oppR ` R ) | 
						
							| 5 | 4 | opprring |  |-  ( R e. Ring -> ( oppR ` R ) e. Ring ) | 
						
							| 6 | 5 | adantr |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> ( oppR ` R ) e. Ring ) | 
						
							| 7 |  | simpr1 |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> N e. ZZ ) | 
						
							| 8 |  | simpr3 |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> Y e. B ) | 
						
							| 9 |  | simpr2 |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> X e. 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 ) e. Ring /\ ( N e. ZZ /\ Y e. B /\ X e. 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 e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. 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 .X. ( N ( .g ` ( oppR ` R ) ) Y ) ) | 
						
							| 16 | 1 3 4 12 | opprmul |  |-  ( Y ( .r ` ( oppR ` R ) ) X ) = ( X .X. Y ) | 
						
							| 17 | 16 | oveq2i |  |-  ( N ( .g ` ( oppR ` R ) ) ( Y ( .r ` ( oppR ` R ) ) X ) ) = ( N ( .g ` ( oppR ` R ) ) ( X .X. Y ) ) | 
						
							| 18 | 14 15 17 | 3eqtr3g |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> ( X .X. ( N ( .g ` ( oppR ` R ) ) Y ) ) = ( N ( .g ` ( oppR ` R ) ) ( X .X. Y ) ) ) | 
						
							| 19 | 1 | a1i |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> B = ( Base ` R ) ) | 
						
							| 20 | 10 | a1i |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> B = ( Base ` ( oppR ` R ) ) ) | 
						
							| 21 |  | ssv |  |-  B C_ _V | 
						
							| 22 | 21 | a1i |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> B C_ _V ) | 
						
							| 23 |  | ovexd |  |-  ( ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) /\ ( x e. _V /\ y e. _V ) ) -> ( x ( +g ` R ) y ) e. _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 e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) /\ ( x e. _V /\ y e. _V ) ) -> ( x ( +g ` R ) y ) = ( x ( +g ` ( oppR ` R ) ) y ) ) | 
						
							| 28 | 2 11 19 20 22 23 27 | mulgpropd |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> .x. = ( .g ` ( oppR ` R ) ) ) | 
						
							| 29 | 28 | oveqd |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> ( N .x. Y ) = ( N ( .g ` ( oppR ` R ) ) Y ) ) | 
						
							| 30 | 29 | oveq2d |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> ( X .X. ( N .x. Y ) ) = ( X .X. ( N ( .g ` ( oppR ` R ) ) Y ) ) ) | 
						
							| 31 | 28 | oveqd |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> ( N .x. ( X .X. Y ) ) = ( N ( .g ` ( oppR ` R ) ) ( X .X. Y ) ) ) | 
						
							| 32 | 18 30 31 | 3eqtr4d |  |-  ( ( R e. Ring /\ ( N e. ZZ /\ X e. B /\ Y e. B ) ) -> ( X .X. ( N .x. Y ) ) = ( N .x. ( X .X. Y ) ) ) |