Ответ:

1) 12 − x = 1 1/9.

x = 12 − 1 1/9 = 10 8/9.

2) 5 8/9 + x = 7 1/18.

x = 7 1/18 − 5 8/9 = 7 1/18 − 5 16/18 = 1 3/18 = 1 1/6.

Ответ: x = 10 8/9; x = 1 1/6.