# Chapter 2 - Section 2.3 - Writing Equations of Lines - 2.3 Exercises - Page 172: 20

$y=-x-3$

#### Work Step by Step

A $y-$intecept of $( 0,-3 )$ implies that $b= -3 .$ Using $y=mx+b$ or the slope-intercept form of linear equations where $b$ is the $y-$intercept and $m$ is the slope, the equation of the line with $m= -1 ,$ and $b= -3$ is \begin{array}{l}\require{cancel} y=-x-3 .\end{array}

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