| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mulgsubdir.b |  | 
						
							| 2 |  | mulgsubdir.t |  | 
						
							| 3 |  | mulgsubdir.d |  | 
						
							| 4 |  | znegcl |  | 
						
							| 5 |  | eqid |  | 
						
							| 6 | 1 2 5 | mulgdir |  | 
						
							| 7 | 4 6 | syl3anr2 |  | 
						
							| 8 |  | simpr1 |  | 
						
							| 9 | 8 | zcnd |  | 
						
							| 10 |  | simpr2 |  | 
						
							| 11 | 10 | zcnd |  | 
						
							| 12 | 9 11 | negsubd |  | 
						
							| 13 | 12 | oveq1d |  | 
						
							| 14 |  | eqid |  | 
						
							| 15 | 1 2 14 | mulgneg |  | 
						
							| 16 | 15 | 3adant3r1 |  | 
						
							| 17 | 16 | oveq2d |  | 
						
							| 18 | 1 2 | mulgcl |  | 
						
							| 19 | 18 | 3adant3r2 |  | 
						
							| 20 | 1 2 | mulgcl |  | 
						
							| 21 | 20 | 3adant3r1 |  | 
						
							| 22 | 1 5 14 3 | grpsubval |  | 
						
							| 23 | 19 21 22 | syl2anc |  | 
						
							| 24 | 17 23 | eqtr4d |  | 
						
							| 25 | 7 13 24 | 3eqtr3d |  |