| Step | Hyp | Ref | Expression | 
						
							| 1 |  | readdcl |  | 
						
							| 2 |  | addcl |  | 
						
							| 3 |  | simp2l |  | 
						
							| 4 |  | simp2r |  | 
						
							| 5 | 3 4 | addcld |  | 
						
							| 6 | 5 | abscld |  | 
						
							| 7 | 3 | abscld |  | 
						
							| 8 | 4 | abscld |  | 
						
							| 9 | 7 8 | readdcld |  | 
						
							| 10 |  | simp1l |  | 
						
							| 11 |  | simp1r |  | 
						
							| 12 | 10 11 | readdcld |  | 
						
							| 13 | 3 4 | abstrid |  | 
						
							| 14 |  | simp3l |  | 
						
							| 15 |  | simp3r |  | 
						
							| 16 | 7 8 10 11 14 15 | le2addd |  | 
						
							| 17 | 6 9 12 13 16 | letrd |  | 
						
							| 18 | 17 | 3expia |  | 
						
							| 19 | 1 2 18 | o1of2 |  |