Description: Sal identifies the constant of proportionality from equations. We are asked, "What is the constant of proportionality in the equation 4y is equal to 8x?" Pause this video and have a go at this question. Well, if we wanna solve for y, we can just divide both sides by four, and we are left with y is equal to eight divided by four, which is two times x.*Teacher Advisor is 100% free.