Question 179607
x=-3y
:
so for this equation, as well as any other line equation we have to isolate the y on one side of the equals and the x  and constant term on the other side
In order to do that  with this equation:
:
-3y=x
:
y=(-1/3)x+0 ...divided by -3 on both sides. I put the zero there to show that in this case the b(y intercept ) is zero.
:
Now, the coefficent in from of the x term is the slope. In our case it is 
(-1/3)
:
{{{graph(300,300,-10,10,-10,10,(-1/3)x)}}}