1) 5-3x 4x-1 ------- -- --------- = -4 7 52) x+4

Найдем корешки.

1) (5 3 * x)/7 - (4 * x 1)/5 = -4;  

(5 * (5 3 * x) 7 * (4 * x 1))/35 = -4;

Скобки раскроем.

(5 * 5 5 * 3 * x 7 * 4 * x + 7 * 1)/35 = -4;

(25 15 * x 28 * x + 7)/35 = -4;

(32 43 * x)/35 = -4;

Умножим значения накрест. 

32 43 * x = -4 * 35;

32 43 * x = -140;

43 * x = 32 + 140;

43 * x = 172;

x = 172/43;

x = 4.

2) (x + 4)/6 - (9 7 * x)/15 = -3;

Умножим на 30.

(x + 4)/6 * 30 30 * (9 7 * x)/15 = -3 * 30;

5 * (x + 4) 2 * (9 7 * x) = -90;

5 * x + 5 * 4 2 * 9 + 2 * 7 * x = -90;

5 * x + 20 18 + 14 * x = -90;

19 * x + 2 = -90;

19 * x = -90 2;

19 * x = -92;

x = -92/19.