12) log₀.₃ \frac{10}{3};

12) $$log_{0.3} \frac{10}{3} = log_{\frac{3}{10}} \frac{10}{3} = log_{\frac{3}{10}} (\frac{3}{10})^{-1} = -log_{\frac{3}{10}} \frac{3}{10} = -1$$

Ответ: -1