Chapter 5 - Section 5.4 - Polynomials in Several Variables - Exercise Set - Page 375: 31

$45x^{2}y+18xy^{2}$

Using the Distributive Property, the product of the given expression, $ 9xy(5x+2y) ,$ is \begin{array}{l}\require{cancel} 9xy(5x)+9xy(2y) \\\\= 45x^{1+1}y+18xy^{1+1} \\\\= 45x^{2}y+18xy^{2} .\end{array}