Answer
$\dfrac{x^{2}}{625y^{4}z^{4}}$
Work Step by Step
Using laws of exponents, then,
\begin{array}{l}
(5xyz)^{-4}(x^{-2})^{-3}
\\\\=
(5^{-4}x^{-4}y^{-4}z^{-4})(x^{-2(-3)})
\\\\=
(5^{-4}x^{-4}y^{-4}z^{-4})(x^{6})
\\\\=
5^{-4}x^{-4+6}y^{-4}z^{-4}
\\\\=
5^{-4}x^{2}y^{-4}z^{-4}
\\\\=
\dfrac{x^{2}}{5^{4}y^{4}z^{4}}
\\\\=
\dfrac{x^{2}}{625y^{4}z^{4}}
.\end{array}
