Решим уравнение:$$3x - 2(3x + 4) = 10$$$$3x - 6x - 8 = 10$$$$-3x - 8 = 10$$$$-3x = 10 + 8$$$$-3x = 18$$$$x = \frac{18}{-3}$$$$x = -6$$
Ответ: -6