| Step | Hyp | Ref | Expression | 
						
							| 1 |  | simp3 |  | 
						
							| 2 |  | nn0uz |  | 
						
							| 3 | 1 2 | eleqtrdi |  | 
						
							| 4 |  | seqp1 |  | 
						
							| 5 | 3 4 | syl |  | 
						
							| 6 |  | fvex |  | 
						
							| 7 |  | fvex |  | 
						
							| 8 | 6 7 | opco1i |  | 
						
							| 9 | 5 8 | eqtrdi |  | 
						
							| 10 |  | eqid |  | 
						
							| 11 | 10 | dvnfval |  | 
						
							| 12 | 11 | 3adant3 |  | 
						
							| 13 | 12 | fveq1d |  | 
						
							| 14 |  | fvex |  | 
						
							| 15 |  | oveq2 |  | 
						
							| 16 |  | ovex |  | 
						
							| 17 | 15 10 16 | fvmpt |  | 
						
							| 18 | 14 17 | ax-mp |  | 
						
							| 19 | 12 | fveq1d |  | 
						
							| 20 | 19 | fveq2d |  | 
						
							| 21 | 18 20 | eqtr3id |  | 
						
							| 22 | 9 13 21 | 3eqtr4d |  |