Chapter 1 - Introduction to Algebraic Expressions - 1.8 Exponential Notation and Order of Operations - 1.8 Exercise Set - Page 67: 103

$9y-25z$

Using $a(b+c)=ab+ac$ or the Distributive Property, the given expression, $ 15x-y-5(3x-2y+5z) $, is equivalent to \begin{array}{l}\require{cancel} 15x-y-5(3x)-5(-2y)-5(5z) \\\\= 15x-y-15x+10y-25z .\end{array} By combining like terms, then this simplifies to \begin{array}{l}\require{cancel} (15x-15x)+(-y+10y)-25z \\\\= 9y-25z .\end{array}