Since your relation is a direct variation then the points on your line are of the form y=kx where k is the constant of variation (also called constant of proportionality)
If y=kx then y/x=k.
So all the points in this relation since it is a direct variation will be equal to y-coordinate/x-coordinate.
So we are going to solve this proportion:
Again I put y/x from each point. They should have same ratio because this is a direct variation.