(3/5x - 2/3) x 15 = 8

15(3/5x-2/3)=8
9x-10=8
9x=18
x=2

(3/5х - 2/3) * 15 = 8
45/5х - 30/3 = 8
9х - 10 = 8
9х = 8 + 10
х = 18 : 9
х = 2
проверка: (3/5 * 2 - 2/3) * 15 = 8
                (6/5 - 2/3) * 15 = 8
                (18/15 - 10/15) * 15 = 8
                 8/15 * 15 = 8
                 8 = 8
Ответ: х = 2.