Description: Sal graphs the equation of a line that represents a proportional relationship given a unit rate. Created by Sal Khan. Graph the line that represents a proportional relationship between y and x with a unit rate 0.4. So when we're thinking about proportional relationships, that means that y is going to be equal to some constant times x. So if we have a proportional relationship, if you have zero x's, it doesn't matter what your constant here is, you're going to have zero y's.*Teacher Advisor is 100% free.