Answer: if you have a function two sets of points (Y1,X1) and (Y2,X2), then the slope that connects this two sets is A= \(\frac{(Y2 -Y1)}{X2 - X1}\)
then Y1 = \(\frac{(Y2 -Y1)}{X2 - X1}\)X1 + b
and Y2 = \(\frac{(Y2 -Y1)}{X2 - X1}\)X2 + b
where b is a random real constant, called the y-intercept.
