| Step | Hyp | Ref | Expression | 
						
							| 1 |  | drngpropd.1 |  | 
						
							| 2 |  | drngpropd.2 |  | 
						
							| 3 |  | drngpropd.3 |  | 
						
							| 4 |  | drngpropd.4 |  | 
						
							| 5 | 1 2 4 | unitpropd |  | 
						
							| 6 | 5 | adantr |  | 
						
							| 7 | 1 2 | eqtr3d |  | 
						
							| 8 | 7 | adantr |  | 
						
							| 9 | 1 | adantr |  | 
						
							| 10 | 2 | adantr |  | 
						
							| 11 | 3 | adantlr |  | 
						
							| 12 | 9 10 11 | grpidpropd |  | 
						
							| 13 | 12 | sneqd |  | 
						
							| 14 | 8 13 | difeq12d |  | 
						
							| 15 | 6 14 | eqeq12d |  | 
						
							| 16 | 15 | pm5.32da |  | 
						
							| 17 | 1 2 3 4 | ringpropd |  | 
						
							| 18 | 17 | anbi1d |  | 
						
							| 19 | 16 18 | bitrd |  | 
						
							| 20 |  | eqid |  | 
						
							| 21 |  | eqid |  | 
						
							| 22 |  | eqid |  | 
						
							| 23 | 20 21 22 | isdrng |  | 
						
							| 24 |  | eqid |  | 
						
							| 25 |  | eqid |  | 
						
							| 26 |  | eqid |  | 
						
							| 27 | 24 25 26 | isdrng |  | 
						
							| 28 | 19 23 27 | 3bitr4g |  |