Answer
$\dfrac{y^5}{2x^3}$
Work Step by Step
Using the properties of radicals, the expression $
\sqrt[4]{\dfrac{y^{20}}{16x^{12}}}
$ simplifies to
\begin{array}{l}
\sqrt[4]{\dfrac{(y^5)^{4}}{2^4(x^3)^4}}
\\\\=
\dfrac{y^5}{2x^3}
.\end{array}