#### Answer

$\frac{y^{5}}{2x^{3}}$

#### Work Step by Step

$\sqrt[4] \frac{y^{20}}{16x^{12}}$
=$\sqrt[4] \frac{y^{20}}{2^{4}\times x^{12}}$
=$\frac{(y^{20})^{\frac{1}{4}}}{(2^{4})^{\frac{1}{4}}\times (x^{12})^{\frac{1}{4}}}$
=$\frac{y^{5}}{2\times x^{3}}$
=$\frac{y^{5}}{2x^{3}}$