Answer
$\sqrt \frac{6n}{5m}$
Work Step by Step
The product rule holds that $\sqrt[n] a\times\sqrt[n] b=\sqrt[n] (ab)$ (where $\sqrt[n] a$ and $\sqrt[n] b$ are real numbers).
Therefore, $\sqrt \frac{6}{m}\times\sqrt \frac{n}{5}=\sqrt (\frac{6}{m}\times\frac{n}{5})=\sqrt \frac{6n}{5m}$