Description: Sal identifies the constant of proportionality from a line graphed on a coordinate plane. And just as a reminder, when we're talking about constant of proportionality, it sounds like a very fancy thing, but it's not too bad. If we're thinking about any X-Y pair on this, on this line, let's say, right over here. If Y is proportionate, or is proportional to X, then that means we can say that Y is equal to some constant.*Teacher Advisor is 100% free.