| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mulgass3.b |  | 
						
							| 2 |  | mulgass3.m |  | 
						
							| 3 |  | mulgass3.t |  | 
						
							| 4 |  | eqid |  | 
						
							| 5 | 4 | opprring |  | 
						
							| 6 | 5 | adantr |  | 
						
							| 7 |  | simpr1 |  | 
						
							| 8 |  | simpr3 |  | 
						
							| 9 |  | simpr2 |  | 
						
							| 10 | 4 1 | opprbas |  | 
						
							| 11 |  | eqid |  | 
						
							| 12 |  | eqid |  | 
						
							| 13 | 10 11 12 | mulgass2 |  | 
						
							| 14 | 6 7 8 9 13 | syl13anc |  | 
						
							| 15 | 1 3 4 12 | opprmul |  | 
						
							| 16 | 1 3 4 12 | opprmul |  | 
						
							| 17 | 16 | oveq2i |  | 
						
							| 18 | 14 15 17 | 3eqtr3g |  | 
						
							| 19 | 1 | a1i |  | 
						
							| 20 | 10 | a1i |  | 
						
							| 21 |  | ssv |  | 
						
							| 22 | 21 | a1i |  | 
						
							| 23 |  | ovexd |  | 
						
							| 24 |  | eqid |  | 
						
							| 25 | 4 24 | oppradd |  | 
						
							| 26 | 25 | oveqi |  | 
						
							| 27 | 26 | a1i |  | 
						
							| 28 | 2 11 19 20 22 23 27 | mulgpropd |  | 
						
							| 29 | 28 | oveqd |  | 
						
							| 30 | 29 | oveq2d |  | 
						
							| 31 | 28 | oveqd |  | 
						
							| 32 | 18 30 31 | 3eqtr4d |  |