Ans: C
$\begin{array}{cl}
& \dfrac{6x}{(3x^{-5})^{-2}}\\
= & \dfrac{6x}{3^{-2}x^{-5\times -2}} \\
= & \dfrac{6x \times 9}{x^{10}} \\
= & \dfrac{54}{x^9}
\end{array}$
$\begin{array}{cl}
& \dfrac{6x}{(3x^{-5})^{-2}}\\
= & \dfrac{6x}{3^{-2}x^{-5\times -2}} \\
= & \dfrac{6x \times 9}{x^{10}} \\
= & \dfrac{54}{x^9}
\end{array}$
