Chapter 1 - Introduction to Algebraic Expressions - 1.8 Exponential Notation and Order of Operations - 1.8 Exercise Set - Page 67: 108

$-20a^2+29ab+48b^2$

Using $a(b+c)=ab+ac$ or the Distributive Property, the given expression, $ -8a^2+5ab-12b^2-6(2a^2-4ab-10b^2) $, is equivalent to \begin{array}{l}\require{cancel} -8a^2+5ab-12b^2-6(2a^2)-6(-4ab)-6(-10b^2) \\\\= -8a^2+5ab-12b^2-12a^2+24ab+60b^2 .\end{array} By combining like terms, then this simplifies to \begin{array}{l}\require{cancel} (-8a^2-12a^2)+(5ab+24ab)+(-12b^2+60b^2) \\\\= -20a^2+29ab+48b^2 .\end{array}