Chapter 1 - Some Basic Concepts of Arithmetic and Algebra - 1.5 - Use of Properties - Problem Set 1.5 - Page 34: 74

$-32$

Combining like terms, the given expression, $ 4xy-5-8xy+9 ,$ simplifies to \begin{array}{l}\require{cancel} (4xy-8xy)+(-5+9) \\\\= -4xy+4 .\end{array} Substituting $ x=-3 $ and $ y=-3 ,$ the resulting expression above evaluates to \begin{array}{l}\require{cancel} -4(-3)(-3)+4 \\\\= -36+4 \\\\= -32 .\end{array}