Ans: $\dfrac{x^{23}}{y^3}$
$\begin{array}{cl}
& \dfrac{x^2}{(x^{-7}y)^3} \\
= & \dfrac{x^2}{x^{(-7)\times 3}y^3} \\
= & \dfrac{x^2}{x^{-21}y^3} \\
= & \dfrac{x^{2-(-21)}}{y^3} \\
= & \dfrac{x^{23}}{y^3}
\end{array}$
$\begin{array}{cl}
& \dfrac{x^2}{(x^{-7}y)^3} \\
= & \dfrac{x^2}{x^{(-7)\times 3}y^3} \\
= & \dfrac{x^2}{x^{-21}y^3} \\
= & \dfrac{x^{2-(-21)}}{y^3} \\
= & \dfrac{x^{23}}{y^3}
\end{array}$
