| Step | Hyp | Ref | Expression | 
						
							| 1 |  | rng2idlring.r |  |-  ( ph -> R e. Rng ) | 
						
							| 2 |  | rng2idlring.i |  |-  ( ph -> I e. ( 2Ideal ` R ) ) | 
						
							| 3 |  | rng2idlring.j |  |-  J = ( R |`s I ) | 
						
							| 4 |  | rng2idlring.u |  |-  ( ph -> J e. Ring ) | 
						
							| 5 |  | rng2idlring.b |  |-  B = ( Base ` R ) | 
						
							| 6 |  | rng2idlring.t |  |-  .x. = ( .r ` R ) | 
						
							| 7 |  | rng2idlring.1 |  |-  .1. = ( 1r ` J ) | 
						
							| 8 | 2 | adantr |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> I e. ( 2Ideal ` R ) ) | 
						
							| 9 | 3 6 | ressmulr |  |-  ( I e. ( 2Ideal ` R ) -> .x. = ( .r ` J ) ) | 
						
							| 10 | 8 9 | syl |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> .x. = ( .r ` J ) ) | 
						
							| 11 | 10 | oveqd |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> ( ( .1. .x. A ) .x. .1. ) = ( ( .1. .x. A ) ( .r ` J ) .1. ) ) | 
						
							| 12 |  | eqid |  |-  ( Base ` J ) = ( Base ` J ) | 
						
							| 13 |  | eqid |  |-  ( .r ` J ) = ( .r ` J ) | 
						
							| 14 | 4 | adantr |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> J e. Ring ) | 
						
							| 15 | 1 2 3 4 5 6 7 | rngqiprngghmlem1 |  |-  ( ( ph /\ A e. B ) -> ( .1. .x. A ) e. ( Base ` J ) ) | 
						
							| 16 | 15 | adantrr |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> ( .1. .x. A ) e. ( Base ` J ) ) | 
						
							| 17 | 12 13 7 14 16 | ringridmd |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> ( ( .1. .x. A ) ( .r ` J ) .1. ) = ( .1. .x. A ) ) | 
						
							| 18 | 11 17 | eqtrd |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> ( ( .1. .x. A ) .x. .1. ) = ( .1. .x. A ) ) | 
						
							| 19 | 18 | oveq1d |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> ( ( ( .1. .x. A ) .x. .1. ) .x. C ) = ( ( .1. .x. A ) .x. C ) ) | 
						
							| 20 | 1 | adantr |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> R e. Rng ) | 
						
							| 21 | 1 2 3 4 5 6 7 | rngqiprng1elbas |  |-  ( ph -> .1. e. B ) | 
						
							| 22 | 21 | adantr |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> .1. e. B ) | 
						
							| 23 |  | simprl |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> A e. B ) | 
						
							| 24 | 5 6 | rngcl |  |-  ( ( R e. Rng /\ .1. e. B /\ A e. B ) -> ( .1. .x. A ) e. B ) | 
						
							| 25 | 20 22 23 24 | syl3anc |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> ( .1. .x. A ) e. B ) | 
						
							| 26 |  | simprr |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> C e. B ) | 
						
							| 27 | 5 6 | rngass |  |-  ( ( R e. Rng /\ ( ( .1. .x. A ) e. B /\ .1. e. B /\ C e. B ) ) -> ( ( ( .1. .x. A ) .x. .1. ) .x. C ) = ( ( .1. .x. A ) .x. ( .1. .x. C ) ) ) | 
						
							| 28 | 20 25 22 26 27 | syl13anc |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> ( ( ( .1. .x. A ) .x. .1. ) .x. C ) = ( ( .1. .x. A ) .x. ( .1. .x. C ) ) ) | 
						
							| 29 | 5 6 | rngass |  |-  ( ( R e. Rng /\ ( .1. e. B /\ A e. B /\ C e. B ) ) -> ( ( .1. .x. A ) .x. C ) = ( .1. .x. ( A .x. C ) ) ) | 
						
							| 30 | 20 22 23 26 29 | syl13anc |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> ( ( .1. .x. A ) .x. C ) = ( .1. .x. ( A .x. C ) ) ) | 
						
							| 31 | 19 28 30 | 3eqtr3d |  |-  ( ( ph /\ ( A e. B /\ C e. B ) ) -> ( ( .1. .x. A ) .x. ( .1. .x. C ) ) = ( .1. .x. ( A .x. C ) ) ) |