Description: Learn how to tell proportional relationships by drawing graphs. Key idea: the graph of a proportional relationship is a straight line through the origin. And just as a reminder, a proportional relationship is one where the ratio between the two variables, and let's say we took the ratio between Y and X, you could also go the other way around, the ratio between X and Y. Or you could rewrite it another way, If you were to multiply both sides of this equation times X, you could say in a proportional relationship, Y is always going to be equal to some constant times X. So with that out of the way, let's look at these three relationships.*Teacher Advisor is 100% free.