Ответ:

x = 10 1/2

x = 1 1/6

Пошаговое объяснение:

12-x=1 1/2

12-1 1/2 = x

10 1/2 = x

x = 10 1/2

_____________

5 8/9 + x = 7 1/18

x = 7 1/18 - 5 8/9

x = 127/18 - 53/9

x = 127/18 - 106/18

x = 21/18

x = 1 3/18

x = 1 1/6