B) lg x = 5 lg m+1gn-11g p;

B) $$lg x = 5 lg m + \frac{2}{3} lg n - \frac{1}{4} lg p$$

$$lg x = lg m^5 + lg n^{\frac{2}{3}} - lg p^{\frac{1}{4}}$$ $$lg x = lg (m^5 \cdot \sqrt[3]{n^2}) - lg \sqrt[4]{p}$$ $$lg x = lg \frac{m^5 \sqrt[3]{n^2}}{\sqrt[4]{p}}$$ $$x = \frac{m^5 \sqrt[3]{n^2}}{\sqrt[4]{p}}$$

Ответ: $$\frac{m^5 \sqrt[3]{n^2}}{\sqrt[4]{p}}$$