Question

if you know two points on a line, how can you find the right the rate of change of the variables being graphed?

Answer 1

You divide the difference in y-coordinates by the diffrence in x-coordinates. Or whatever the variables are.

Lets say the coordinates of the two points are (a,b) and (c,d). Then:

Rate of change is "rise/run" = (b - d)/(c - a) = (d - b)/(a - c)