Ans: $\dfrac{n^5}{m^3}$
$\begin{array}{cl}
& \dfrac{m^6}{m^9n^{-5}} \\
= & \dfrac{1}{m^{9-6}n^{-5}} \\
= & \dfrac{1}{m^3n^{-5}} \\
= & \dfrac{n^5}{m^3}
\end{array}$
$\begin{array}{cl}
& \dfrac{m^6}{m^9n^{-5}} \\
= & \dfrac{1}{m^{9-6}n^{-5}} \\
= & \dfrac{1}{m^3n^{-5}} \\
= & \dfrac{n^5}{m^3}
\end{array}$
