7. $$log_{25} 3125 + log_{0.04} 0.008$$

7. $$log_{25} 3125 = log_{5^2} 5^5 = \frac{5}{2}log_5 5 = \frac{5}{2} = 2.5$$. $$log_{0.04} 0.008 = log_{\frac{4}{100}} \frac{8}{1000} = log_{\frac{1}{25}} \frac{1}{125} = log_{5^{-2}} 5^{-3} = \frac{-3}{-2} log_5 5 = \frac{3}{2} = 1.5$$. Тогда $$2.5 + 1.5 = 4$$. Ответ: 4