Verified answer

Пошаговое объяснение:

12/25 + х = 8/15

х = 8/15 - 12/25

х = 40/75 - 36/75

х = 4/75

12/13 - х = 7/26

х = 12/13 - 7/26

х = 24/26 - 7/26

х = 17/26

х - 7/9 = 2/18

х = 2/18 + 7/9

х = 2/18 + 14/18

х = 16/18

х = 8/9