а) 83 63/101 - 19 24/101 = 83•101+63/101 - 19•101+24/101 = 8446/101 - 1943/101 = 8446-1943/101 = 6503/101 = 64 39/101

б) 32 8/21 - 23 7/15 = 32•21+8/21 - 23•15+7/15 = 680/21 - 352/15 = 5•680/5•21 - 7•352/7•15 = 3400/105 - 2464/105 = 3400-2464/105 = 936/105 = 312•3/35•3 = 312/35 = 8 32/35