Explanation:
The slope of a line given two points is found by using one of the following ( they are actually the same thing)
m = slope
m = rise / run see image below rise = 3 run = 5 so m = 3/5
Or you can use the coordinates of A and B
m = (y1-y2) / (x1-x2) = (-2-1) / (0 - 5) = -3/-5 = 3/ 5