25 + (x - 2) * 15 = 70 72 : (12 - x : 4) = 9

1) 25 + (x - 2) * 15 = 70;

15 * (x - 2) = 70 - 25;

15 * (x - 2) = 45;

x - 2 = 45/15;

x - 2 = 3;

x = 3 + 2;

x = 5;

Проверка:

25 + (5 - 2) * 15 = 70;

25 + 3 * 15 = 70;

25 + 5 = 70;

70 = 70;

Верно;

Ответ: х = 5.

2) 72 / (12 - x/4) = 9;

9 * (12 - x/4) = 72;

12 - x/4 = 72/9;

12 - x/4 = 8;

-x/4 = 8 - 12;

-x/4 = - 4;

x/4 = 4;

x = 4 * 4;

x = 16;

Проверка:

72 / (12 - 16/4) = 9;

72 / (12 - 4) = 9;

72/8 = 9;

9 = 9;

Верно;

Ответ: х = 16.