Ответ:

1)

x - 1/4 = 3/7

x = 3/7 + 1/4

x = 12/28 + 7/28

x = 19/28

2)

1/2 - x = 3/8

-x = 3/8 - 1/2

-x = 3/8 - 4/8

-x = -1/8

x = 1/8

3)

y + 4/15 = 5/12

y = 5/12 - 4/15

y = 25/60 - 16/60

y = 9/60

y = 3/20

Пошаговое объяснение: