Ответ:

Пошаговое объяснение:

(х-1 2/5):10+7 5/12=9

(х-1 2/5):10 = 9 - 7 5/12

(х-1 2/5):10 = 1 7/12

x - 1 2/5 = 1 7/12 * 10

x - 1 2/5 = 19/12 * 10

x - 1 2/5 = 95/6

x = 95/6 + 1 2/5

x = 95/6 + 7/5

x = 475/30 + 42/30

x = 517/30

x = 17 7/30