Description: Sal graphs the equation of a line that represents a proportional relationship given an equation. Created by Sal Khan. We're asked to graph y is equal to 2.5 times x. So we really just have to think about two points that satisfy this equation here, and the most obvious one is what happens when x equals 0. When x equals 0, 2.5 times 0 is going to be 0.*Teacher Advisor is 100% free.