Chapter 5 - Summary, Review, and Test - Cumulative Review Exercises (Chapters 1-5) - Page 588: 31

$y=-3x+10$

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: $m=\frac{-2-4}{4-2}=\frac{-6}{2}=-3.$ 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: $y-4=-3(x-2))\\y-4=-3x+6\\y=-3x+10$