8/15-1/2 19 6/7-8 5/8 1 3/26-5/13 7 3/14-2 7/10-2 13/35

8/15 - 1/2 = 16/30 - 15/30 = 1/30 

19 6/7 - 8 5/8 = 19 48/56 - 8 35/56 = 11 целых 13/56

1 3/26 - 5/13 = 29/26 - 10/26 = 19/26

7 3/14 - 2 7/10 - 2 13/35 = 7 15/70 - 2 49/70 - 2 26/70 = 7 15/70 - (2 49/70 + 2 26/70) = 6 85/70 - 4 75/70 = 2 10/70 = 2 целых 1/7