Your question is confusing, do you want the slope between the two points? if so, use the following equation:M = Slope of the LineM=(Y1-Y2)/(X1-X2)that equation should give you the slope of any linear graph using 2 points in that graph.After you have found the slope, use this equation:Y= mx + bY= Y-valuex= x-valueb = y-interceptEX: i'm going to do one example for the pairs you have given me

2,4)

-1,-4)M= (4 + 4) / (2 + 1)M= 8/3Next:Y=(8/3)x + bnow, plug in the x and y value4= (8/3)(2) + b and solve for b4= (16/3) + bb= 4 - (16/3)b= -1.333333...so the equation for the first pair is y=(8/3)x-(4/3)I know it looks complicated, but once you've learned the basic concept then everything will be easy.I hope that helps