Answer
Please see the graph.
Work Step by Step
Let $x=0$
$x=-3y$
$0=-3y$
$0/-3=-3y/-3$
$0=y$
Let $x=-3$
$x=-3y$
$-3=-3y$
$-3/-3=-3y/-3$
$1=y$
Let $x=3$
$x=-3y$
$3=-3y$
$3/-3=-3y/-3$
$-1=y$
Three points on the line are $(0,0), (-3,1),$ and $(3,-1)$.