Chapter 5 - Exponents and Polynomials - 5.6 - Integral Exponents and Scientific Notation - Problem Set 5.6 - Page 224: 74

$\dfrac{x^{6}}{y^{4}}$

Using the laws of exponents, the given expression, $ \left( \dfrac{y^{2}}{x^{3}} \right)^{-2} ,$ is equivalent to \begin{array}{l}\require{cancel} \dfrac{y^{2(-2)}}{x^{3(-2)}} \\\\= \dfrac{y^{-4}}{x^{-6}} \\\\= \dfrac{x^{6}}{y^{4}} .\end{array}