Answer
$\dfrac{m^{10}n^{6}}{9}$
Work Step by Step
Using the laws of exponents, the given expression, $
(3m^{-5}n^{-3})^{-2}
$, is equivalent to
\begin{array}{l}\require{cancel}
3^{-2}m^{-5(-2)}n^{-3(-2)}
\\\\=
3^{-2}m^{10}n^{6}
\\\\=
\dfrac{m^{10}n^{6}}{3^{2}}
\\\\=
\dfrac{m^{10}n^{6}}{9}
.\end{array}