Slope formula: m = (y2 - y1) / (x2 - x1). You subtract the x's and y's of one point from the other.
m = (9 - 3) / (5 - -3)
m = 6 / 8
m = 3 / 4
It doesn't matter which point you use for x1 and y1:
m = (3 - 9) / (-3 - 5)
m = -6 / -8
m = 6 / 8
m = 3 / 4
