Решим уравнение log5(5 - 5x) = 2log52.
$$2log_5 2 = log_5 2^2 = log_5 4$$
$$log_5(5 - 5x) = log_5 4$$
$$5 - 5x = 4$$
$$-5x = 4 - 5$$
$$-5x = -1$$
$$x = \frac{-1}{-5}$$
$$x = \frac{1}{5}$$
Ответ: $$\frac{1}{5}$$