Решим уравнение:
$$log_2(x + 6) = log_2(6x - 11) - 2$$
$$log_2(x + 6) = log_2(6x - 11) - log_2(2^2)$$
$$log_2(x + 6) = log_2(6x - 11) - log_2(4)$$
$$log_2(x + 6) = log_2(\frac{6x - 11}{4})$$
$$x + 6 = \frac{6x - 11}{4}$$
$$4(x + 6) = 6x - 11$$
$$4x + 24 = 6x - 11$$
$$2x = 35$$
$$x = 17.5$$
Ответ: 17.5