| Step | Hyp | Ref | Expression | 
						
							| 1 |  | addmulsub |  | 
						
							| 2 | 1 | 3adant3 |  | 
						
							| 3 | 2 | oveq2d |  | 
						
							| 4 |  | simp3 |  | 
						
							| 5 |  | simp1l |  | 
						
							| 6 |  | simp2l |  | 
						
							| 7 | 5 6 | mulcld |  | 
						
							| 8 |  | simp1r |  | 
						
							| 9 | 8 6 | mulcld |  | 
						
							| 10 | 7 9 | addcld |  | 
						
							| 11 |  | simp2r |  | 
						
							| 12 | 5 11 | mulcld |  | 
						
							| 13 | 8 11 | mulcld |  | 
						
							| 14 | 12 13 | addcld |  | 
						
							| 15 | 4 10 14 | subsubd |  | 
						
							| 16 | 4 7 9 | subsub4d |  | 
						
							| 17 | 16 | eqcomd |  | 
						
							| 18 | 17 | oveq1d |  | 
						
							| 19 | 3 15 18 | 3eqtrd |  |