Открываем скобки:

3.2 * (x - 5) - 6 * (1.5x - 1) = 3.2 * x - 3.2 * 5 - 6 * 1.5x + 6 * 1 = 3.2x - 16 - 9x + 6 = 3.2x - 9x - 16 + 6 = -5.8x- 10.