Rewrite the square root of the division $\frac{16}{81}$ as the division of square roots $\frac{\sqrt{16}}{\sqrt{81}}$. Take the square root of both numerator and denominator.
$$\frac{4}{9}\sqrt[5]{\frac{243}{32}}$$
Calculate $\sqrt[5]{\frac{243}{32}}$ and get $\frac{3}{2}$.
$$\frac{4}{9}\times \frac{3}{2}$$
Multiply $\frac{4}{9}$ and $\frac{3}{2}$ to get $\frac{2}{3}$.
