4. Решите уравнение:а) 4x + (3x - 5) = 3x +15; б) 2(3x-2)-3(4x - 3) = 2 - 4x

а)

$$4x + (3x - 5) = 3x + 15$$

$$4x + 3x - 5 = 3x + 15$$

$$7x - 5 = 3x + 15$$

$$7x - 3x = 15 + 5$$

$$4x = 20$$

$$x = \frac{20}{4}$$

$$x = 5$$

Ответ: $$5$$

б)

$$2(3x - 2) - 3(4x - 3) = 2 - 4x$$

$$6x - 4 - 12x + 9 = 2 - 4x$$

$$-6x + 5 = 2 - 4x$$

$$-6x + 4x = 2 - 5$$

$$-2x = -3$$

$$x = \frac{-3}{-2}$$

$$x = 1.5$$

Ответ: $$1.5$$