Chapter 7 - Summary, Review, and Test - Cumulative Review Exercises (Chapters 1-7) - Page 7074: 18

$y=-2x-2$

We know that by the Slope Formula: if $P_1(x_1,y_1)$ and $P_2(x_2,y_2)$ are on a line, then the slope is: $m=\frac{y_2-y_1}{x_2-x_1}$. Hence here: $m=\frac{8-(-4)}{-5-1}=-2.$ We know that if the slope of a line is $m$ and it contains $P_1(x_1,y_1)$, then its equation is: $y-y_1=m(x-x_1).$ Hence here: $y-8=-2(x-(-5))\\y-8=-2x-10\\y=-2x-2$