Use rise over run to find slope. If you don't know what that is, its y2-y1/x2-x1. Y2 is 125, Y1 is 25, X2 is 5, and X1 is 1. You then plug the numbers in, 125-25=100. 5-1=4. then you divide 100/4, in which you get 25. So you times 25 by 3, getting 75.
