(7, 8) and (0, 4)
m = 4/7
(-2, 5) and (4, 1)
m = -2/3
(-9, 3) and (-9, 6)
m = undefined or no slope
(12, 2) and (0, -4)
m = 1/2
(5, 3) and (4, 2)
m = 1
(-2, 6) and (4, 6)
m = 0
(2, 6) and (3, -6)
m = -12
(1, 6) and (9, 3)
m = -3/8
(11, 10) and (1, 2)
m = 4/5
(1, 9) and (3, 3)
m = -3