6. 5 – 7x = 11x – 3(x + 5).

6. Решим уравнение:

$$5 - 7x = 11x - 3(x + 5)$$

$$5 - 7x = 11x - 3x - 15$$

$$5 - 7x = 8x - 15$$

$$8x + 7x = 5 + 15$$

$$15x = 20$$

$$x = \frac{20}{15} = \frac{4}{3}$$

Ответ: $$x = \frac{4}{3}$$