# Chapter 1 - Some Basic Concepts of Arithmetic and Algebra - Chapter 1 Review Problem Set: 56

$-57$

#### Work Step by Step

Substituting $x= -3$ and $y= 4$, the given expression, $7x-9y ,$ evaluates to \begin{array}{l}\require{cancel} 7(-3)-9(4) \\\\= -21-36 \\\\= -57 .\end{array}

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