3 2/15 - 1 1/7 = 47/15 - 8/7 =(47 × 7 - 8 × 15)/105 = 329/105 - 120/105 = 209/105 = 1 104/1055/34 - 41 =5/34-41/1=(5 × 1 - 41 × 34)/34 = 5/34 - 1394/34 = - 1389/34 = - 40 29/34
3 1/30 - 5 7/90 = 91/30 - 457/90 = (91 × 3 - 457 × 1)/90 = 273/90 - 457/90 = - 184/90 = - 92/45 = - 2 2/45
6 1/7 - 10 3/4 = 43/7 - 43/4 =(43 × 4 - 43 × 7)/28 = 172/28 - 301/28 = - 129/28 = - 4 17/28