Chapter 5 - Section 5.2 - More Work with Exponents and Scientific Notation - Exercise Set - Page 268: 39

$\dfrac{x^{9}}{8y^{3}}$

Using laws of exponents, the given expression simplifies to \begin{align*} & \left( \dfrac{2x^{-3}}{y^{-1}} \right)^{-3} \\\\&= \dfrac{2^{-3}x^{-3(-3)}}{y^{-1(-3)}} \\\\&= \dfrac{2^{-3}x^{9}}{y^{3}} \\\\&= \dfrac{x^{9}}{2^{3}y^{3}} \\\\&= \dfrac{x^{9}}{8y^{3}} .\end{align*}