Each time the line makes a “stop” at an intersection of graph lines, make a point. Count how many it takes to go up and across from one point to another. Think of it as a fraction: top number is how many it takes to go up, bottom number is how many it takes to go across. If top number is going up, then it is positive. If it is going down, it is a negative number. So the answer is STEEPEST slope is 2, LEAST steep is 1/5, and the MIDDLE one is 1.
