| Step | Hyp | Ref | Expression | 
						
							| 1 |  | znegcl |  | 
						
							| 2 |  | fzoaddel |  | 
						
							| 3 | 1 2 | sylan2 |  | 
						
							| 4 |  | elfzoelz |  | 
						
							| 5 | 4 | adantr |  | 
						
							| 6 | 5 | zcnd |  | 
						
							| 7 |  | simpr |  | 
						
							| 8 | 7 | zcnd |  | 
						
							| 9 | 6 8 | negsubd |  | 
						
							| 10 |  | elfzoel1 |  | 
						
							| 11 | 10 | adantr |  | 
						
							| 12 | 11 | zcnd |  | 
						
							| 13 | 12 8 | negsubd |  | 
						
							| 14 |  | elfzoel2 |  | 
						
							| 15 | 14 | adantr |  | 
						
							| 16 | 15 | zcnd |  | 
						
							| 17 | 16 8 | negsubd |  | 
						
							| 18 | 13 17 | oveq12d |  | 
						
							| 19 | 3 9 18 | 3eltr3d |  |