Ans: $\dfrac{m^{26}}{n^9}$
$\begin{array}{rl}
& \dfrac{(m^5n^{-2})^6}{m^4n^{-3}} \\
= & \dfrac{m^{30}n^{-12}}{m^4n^{-3}} \\
= & m^{30-4}n^{-12-(-3)} \\
= & m^{26}n^{-9} \\
= & \dfrac{m^{26}}{n^9}
\end{array}$
$\begin{array}{rl}
& \dfrac{(m^5n^{-2})^6}{m^4n^{-3}} \\
= & \dfrac{m^{30}n^{-12}}{m^4n^{-3}} \\
= & m^{30-4}n^{-12-(-3)} \\
= & m^{26}n^{-9} \\
= & \dfrac{m^{26}}{n^9}
\end{array}$
