Chapter 1 - Introduction to Algebraic Expressions - 1.8 Exponential Notation and Order of Operations - 1.8 Exercise Set - Page 67: 110

$9t^4-45t^3+17t$

Using $a(b+c)=ab+ac$ or the Distributive Property, the given expression, $ 9t^4+7t-5(9t^3-2t) $, is equivalent to \begin{array}{l}\require{cancel} 9t^4+7t-5(9t^3)-5(-2t) \\\\= 9t^4+7t-45t^3+10t .\end{array} By combining like terms, then this simplifies to \begin{array}{l}\require{cancel} 9t^4-45t^3+(7t+10t) \\\\= 9t^4-45t^3+17t .\end{array}