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
