Answer
$\dfrac{z^{4}}{x^3}$
Work Step by Step
Using the laws of exponents, the given expression, $
(z^{-4}x^3)^{-1}
,$ is equivalent to
\begin{array}{l}\require{cancel}
z^{-4(-1)}x^{3(-1)}
\\\\=
z^{4}x^{-3}
\\\\=
\dfrac{z^{4}}{x^3}
.\end{array}