Answer
Please see image
Work Step by Step
$x+3y=0$
$3y=-x$
$y=-\displaystyle \frac{1}{3}x$
The y intercept is 0 (the line passes through the origin)
One more point needed (two points determine a line).
When x=$3$,
y=$-\displaystyle \frac{1}{3}\cdot 3=-1$
So, another point on the line is ($3,-1$).
Plot the two points and draw a straight line through them
