| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ringnegmul.1 |  |-  G = ( 1st ` R ) | 
						
							| 2 |  | ringnegmul.2 |  |-  H = ( 2nd ` R ) | 
						
							| 3 |  | ringnegmul.3 |  |-  X = ran G | 
						
							| 4 |  | ringnegmul.4 |  |-  N = ( inv ` G ) | 
						
							| 5 | 1 | rneqi |  |-  ran G = ran ( 1st ` R ) | 
						
							| 6 | 3 5 | eqtri |  |-  X = ran ( 1st ` R ) | 
						
							| 7 |  | eqid |  |-  ( GId ` H ) = ( GId ` H ) | 
						
							| 8 | 6 2 7 | rngo1cl |  |-  ( R e. RingOps -> ( GId ` H ) e. X ) | 
						
							| 9 | 1 3 4 | rngonegcl |  |-  ( ( R e. RingOps /\ ( GId ` H ) e. X ) -> ( N ` ( GId ` H ) ) e. X ) | 
						
							| 10 | 8 9 | mpdan |  |-  ( R e. RingOps -> ( N ` ( GId ` H ) ) e. X ) | 
						
							| 11 | 1 2 3 | rngoass |  |-  ( ( R e. RingOps /\ ( ( N ` ( GId ` H ) ) e. X /\ A e. X /\ B e. X ) ) -> ( ( ( N ` ( GId ` H ) ) H A ) H B ) = ( ( N ` ( GId ` H ) ) H ( A H B ) ) ) | 
						
							| 12 | 11 | 3exp2 |  |-  ( R e. RingOps -> ( ( N ` ( GId ` H ) ) e. X -> ( A e. X -> ( B e. X -> ( ( ( N ` ( GId ` H ) ) H A ) H B ) = ( ( N ` ( GId ` H ) ) H ( A H B ) ) ) ) ) ) | 
						
							| 13 | 10 12 | mpd |  |-  ( R e. RingOps -> ( A e. X -> ( B e. X -> ( ( ( N ` ( GId ` H ) ) H A ) H B ) = ( ( N ` ( GId ` H ) ) H ( A H B ) ) ) ) ) | 
						
							| 14 | 13 | 3imp |  |-  ( ( R e. RingOps /\ A e. X /\ B e. X ) -> ( ( ( N ` ( GId ` H ) ) H A ) H B ) = ( ( N ` ( GId ` H ) ) H ( A H B ) ) ) | 
						
							| 15 | 1 2 3 4 7 | rngonegmn1l |  |-  ( ( R e. RingOps /\ A e. X ) -> ( N ` A ) = ( ( N ` ( GId ` H ) ) H A ) ) | 
						
							| 16 | 15 | 3adant3 |  |-  ( ( R e. RingOps /\ A e. X /\ B e. X ) -> ( N ` A ) = ( ( N ` ( GId ` H ) ) H A ) ) | 
						
							| 17 | 16 | oveq1d |  |-  ( ( R e. RingOps /\ A e. X /\ B e. X ) -> ( ( N ` A ) H B ) = ( ( ( N ` ( GId ` H ) ) H A ) H B ) ) | 
						
							| 18 | 1 2 3 | rngocl |  |-  ( ( R e. RingOps /\ A e. X /\ B e. X ) -> ( A H B ) e. X ) | 
						
							| 19 | 18 | 3expb |  |-  ( ( R e. RingOps /\ ( A e. X /\ B e. X ) ) -> ( A H B ) e. X ) | 
						
							| 20 | 1 2 3 4 7 | rngonegmn1l |  |-  ( ( R e. RingOps /\ ( A H B ) e. X ) -> ( N ` ( A H B ) ) = ( ( N ` ( GId ` H ) ) H ( A H B ) ) ) | 
						
							| 21 | 19 20 | syldan |  |-  ( ( R e. RingOps /\ ( A e. X /\ B e. X ) ) -> ( N ` ( A H B ) ) = ( ( N ` ( GId ` H ) ) H ( A H B ) ) ) | 
						
							| 22 | 21 | 3impb |  |-  ( ( R e. RingOps /\ A e. X /\ B e. X ) -> ( N ` ( A H B ) ) = ( ( N ` ( GId ` H ) ) H ( A H B ) ) ) | 
						
							| 23 | 14 17 22 | 3eqtr4rd |  |-  ( ( R e. RingOps /\ A e. X /\ B e. X ) -> ( N ` ( A H B ) ) = ( ( N ` A ) H B ) ) |