The constant of proportionality is the ratio between the y-coordinate and the x-coordinate of any point on the graph. Since the point (-4,2) lies on the graph, you can use it to find the constant of proportionality.
The constant of proportionality is the ratio of the y-coordinate to the x-coordinate, which is:
Constant of proportionality = y / x = 2 / (-4) = -0.5
So, the constant of proportionality for this proportional relationship is -0.5.