slope = rise / run
m = (y2 - y1) / (x2 - x1)
m = (5 - -3) / (1 - 2)
m = (5 + 3) / (-1)
m = 8 / (-1)
m = -8
point-slope form, pick one of the points, doesn't matter which one, pick (2, -3)
y - y1 = m (x - x1)
y - -3 = -8 (x - 2)
y + 3 = -8x + 16
y = -8x + 13