| Step | Hyp | Ref | Expression | 
						
							| 1 |  | zncyg.y |  | 
						
							| 2 | 1 | zncrng |  | 
						
							| 3 |  | crngring |  | 
						
							| 4 | 2 3 | syl |  | 
						
							| 5 |  | ringgrp |  | 
						
							| 6 | 4 5 | syl |  | 
						
							| 7 |  | eqid |  | 
						
							| 8 |  | eqid |  | 
						
							| 9 | 7 8 | ringidcl |  | 
						
							| 10 | 4 9 | syl |  | 
						
							| 11 |  | eqid |  | 
						
							| 12 |  | eqid |  | 
						
							| 13 | 11 12 8 | zrhval2 |  | 
						
							| 14 | 4 13 | syl |  | 
						
							| 15 | 14 | rneqd |  | 
						
							| 16 | 1 7 11 | znzrhfo |  | 
						
							| 17 |  | forn |  | 
						
							| 18 | 16 17 | syl |  | 
						
							| 19 | 15 18 | eqtr3d |  | 
						
							| 20 |  | oveq2 |  | 
						
							| 21 | 20 | mpteq2dv |  | 
						
							| 22 | 21 | rneqd |  | 
						
							| 23 | 22 | eqeq1d |  | 
						
							| 24 | 23 | rspcev |  | 
						
							| 25 | 10 19 24 | syl2anc |  | 
						
							| 26 | 7 12 | iscyg |  | 
						
							| 27 | 6 25 26 | sylanbrc |  |