| Step | Hyp | Ref | Expression | 
						
							| 1 |  | metakunt15.1 |  | 
						
							| 2 |  | metakunt15.2 |  | 
						
							| 3 |  | metakunt15.3 |  | 
						
							| 4 |  | metakunt15.4 |  | 
						
							| 5 |  | 1zzd |  | 
						
							| 6 | 2 | nnzd |  | 
						
							| 7 | 6 | adantr |  | 
						
							| 8 | 7 5 | zsubcld |  | 
						
							| 9 | 1 | nnzd |  | 
						
							| 10 | 9 | adantr |  | 
						
							| 11 | 10 7 | zsubcld |  | 
						
							| 12 |  | simpr |  | 
						
							| 13 |  | elfz3 |  | 
						
							| 14 | 11 13 | syl |  | 
						
							| 15 | 11 | zcnd |  | 
						
							| 16 |  | 1cnd |  | 
						
							| 17 | 15 16 | addcomd |  | 
						
							| 18 | 1 | nncnd |  | 
						
							| 19 | 2 | nncnd |  | 
						
							| 20 |  | 1cnd |  | 
						
							| 21 | 18 19 20 | npncand |  | 
						
							| 22 | 21 | eqcomd |  | 
						
							| 23 | 18 19 | subcld |  | 
						
							| 24 | 19 20 | subcld |  | 
						
							| 25 | 23 24 | addcomd |  | 
						
							| 26 | 22 25 | eqtrd |  | 
						
							| 27 | 26 | adantr |  | 
						
							| 28 | 5 8 11 11 12 14 17 27 | fzadd2d |  | 
						
							| 29 |  | 1zzd |  | 
						
							| 30 | 6 | adantr |  | 
						
							| 31 | 30 29 | zsubcld |  | 
						
							| 32 |  | elfzelz |  | 
						
							| 33 | 32 | adantl |  | 
						
							| 34 | 9 | adantr |  | 
						
							| 35 | 34 30 | zsubcld |  | 
						
							| 36 | 33 35 | zsubcld |  | 
						
							| 37 |  | elfzle1 |  | 
						
							| 38 | 37 | adantl |  | 
						
							| 39 | 35 | zred |  | 
						
							| 40 |  | 1red |  | 
						
							| 41 | 33 | zred |  | 
						
							| 42 | 39 40 41 | leaddsub2d |  | 
						
							| 43 | 38 42 | mpbid |  | 
						
							| 44 |  | elfzle2 |  | 
						
							| 45 | 44 | adantl |  | 
						
							| 46 | 21 | adantr |  | 
						
							| 47 | 45 46 | breqtrrd |  | 
						
							| 48 | 31 | zred |  | 
						
							| 49 | 41 39 48 | lesubadd2d |  | 
						
							| 50 | 47 49 | mpbird |  | 
						
							| 51 | 29 31 36 43 50 | elfzd |  | 
						
							| 52 |  | eqcom |  | 
						
							| 53 | 52 | a1i |  | 
						
							| 54 | 32 | zcnd |  | 
						
							| 55 | 54 | ad2antll |  | 
						
							| 56 | 18 | adantr |  | 
						
							| 57 | 19 | adantr |  | 
						
							| 58 | 56 57 | subcld |  | 
						
							| 59 |  | elfznn |  | 
						
							| 60 | 59 | nncnd |  | 
						
							| 61 | 60 | ad2antrl |  | 
						
							| 62 | 55 58 61 | subaddd |  | 
						
							| 63 | 53 62 | bitr3d |  | 
						
							| 64 | 58 61 | addcomd |  | 
						
							| 65 | 64 | eqeq1d |  | 
						
							| 66 |  | eqcom |  | 
						
							| 67 | 66 | a1i |  | 
						
							| 68 | 65 67 | bitrd |  | 
						
							| 69 | 63 68 | bitrd |  | 
						
							| 70 | 4 28 51 69 | f1o2d |  |