2014-I-01

Ans: $\dfrac{x^3}{y^{10}}$
$\begin{array}{cl}
& \dfrac{(xy^{-2})^3}{y^4} \\
= & \dfrac{x^3y^{-2\times 3}}{y^4} \\
= & \dfrac{x^3y^{-6}}{y^4} \\
= & \dfrac{x^3}{y^{4+6}} \\
= & \dfrac{x^3}{y^{10}}
\end{array}$