Chapter 1 - Introduction to Algebraic Expressions - 1.2 The Commutative, Associative, and Distributive Laws - 1.2 Exercise Set - Page 17: 38

$(5x)(2+y)$

$5[x(2+y)]=(5x)(2+y)$ There are three factors in this multiplication problem. They are 5, x and (2+y). The associative property says the factors can be regrouped without impacting the result. In the original expression x is grouped with (2+y). In the rewritten expression x is grouped with 5.