А) 1 5/12 - 9/10 = 1 25/60 - 54/60 = 85/60 - 54/60 = 31/60
б) 9 1/2 - 5 9/17 = 9 17/34 - 5 18/34 = 8 51/34 - 5 18/34 = 3 33/34
в) 3 4/7 - 1 7/9 = 3 36/63 - 1 49/63 = 2 99/63 - 1 49/63 = 1 50/63
г) 7 3/8 - 2 5/6 - 7 9/24 - 2 20/24 = 7 9/24 - 2 20/24 - 7 9/24 - 2 20/24 = - 4 40/24 = - 5 16/24 = - 5 2/3