Ответ:

13/14

Пошаговое объяснение:

1) 3 - 1. 13/14 = 2. 14/14 - 1. 13/14 = 1. 1/14

2) 9/49 : 1. 1/14 = 9/49 : 15/14 = 9/49 * 14/15 = 3/7 * 2/5 = 6/35

3) 7/10 - 6/35 + 2/5 =

49/70 - 12/70 + 28/70 =

65/70 = 13/14