| Step | Hyp | Ref | Expression | 
						
							| 1 |  | drngprop.b |  | 
						
							| 2 |  | drngprop.p |  | 
						
							| 3 |  | drngprop.m |  | 
						
							| 4 |  | eqidd |  | 
						
							| 5 | 1 | a1i |  | 
						
							| 6 | 3 | oveqi |  | 
						
							| 7 | 6 | a1i |  | 
						
							| 8 | 4 5 7 | unitpropd |  | 
						
							| 9 | 2 | oveqi |  | 
						
							| 10 | 9 | a1i |  | 
						
							| 11 | 4 5 10 | grpidpropd |  | 
						
							| 12 | 11 | sneqd |  | 
						
							| 13 | 12 | difeq2d |  | 
						
							| 14 | 8 13 | eqeq12d |  | 
						
							| 15 | 14 | pm5.32i |  | 
						
							| 16 | 1 2 3 | ringprop |  | 
						
							| 17 | 16 | anbi1i |  | 
						
							| 18 | 15 17 | bitri |  | 
						
							| 19 |  | eqid |  | 
						
							| 20 |  | eqid |  | 
						
							| 21 |  | eqid |  | 
						
							| 22 | 19 20 21 | isdrng |  | 
						
							| 23 |  | eqid |  | 
						
							| 24 |  | eqid |  | 
						
							| 25 | 1 23 24 | isdrng |  | 
						
							| 26 | 18 22 25 | 3bitr4i |  |