3 (5-x) +13=4 (3x-8)

3 * (5 - x) + 13 = 4 * (3x - 8);

3 * 5 - х * 3 + 13 = 4 * 3х - 8 * 4;

15 - 3х + 13 = 12х - 32;

28 - 3х = 12х - 32;

- 3х - 12х = - 32 - 28;

- 15х = - 60;

- х = - 60 : 15;

- х = - 4;

- х * (- 1) = - 4 * (- 1);

х = 4;

3 * (5 - 4) + 13 = 4 * (3 * 4 - 8);

3 * 1 + 13 = 4 * (12 - 8);

3 + 13 = 4 * 4;

16 = 16.