Ответ:

- 17/18

Пошаговое объяснение:

x + 2 1/3 + 3 1/9 + 1 1/12 = 5 7/12

x + 2 12/36 + 3 4/36 + 1 3/36 = 5 21/36

x + 6 19/36 = 5 21/36

x = 5 21/36 - 6 19/36

x = 5 21/36 - 5 55/36

x = - 34/36

x = - 17/18