1). (3/5 х-1 1/3) * 15=7; 2). (2/3+5/7 x) * 21=29 и еще 1 задание

1) (3/5 * х - 1 1/3) * 15 = 7;

(3/5 * х - (1 * 3 + 1) / 3) * 15/15 = 7/15;

3/5 * х - 4/3 = 7/15;

3/5 * х = 7/15 + 4/3;

3/5 * х = 7/15 + 20/15;

3/5 * х = 27/15;

3/5 * х * 5/3 = 27/15 * 5/3;

х = (27 * 5) / (15 * 3) = 27 / (3 * 3) = 3.

Ответ: х = 3.

2) (2/3 + 5/7 * x) * 21 = 29;

(2/3 + 5/7 * x) * 21/21 = 29/21;

2/3 + 5/7 * x = 29/21;

5/7 * x = 29/21 - 2/3;

5/7 * x = 29/21 - 14/21;

5/7 * x = 15/21;

x = 15/21 * 7/5 = (15 * 7) / (21 * 5) = 15 / (3 * 5) = 1.

Ответ: х = 1.