slope = rise / run
m = (y2 - y1) / (x2 - x1)
m = (-4 - 4) / (2 - -4)
m = (-8) / (2 + 4)
m = (-8) / (6)
m = -4/3
point-slope form, pick a point, doesn't matter which one, pick (2, -4)
y - y1 = m (x - x1)
y - -4 = (-4/3)(x - 2)
y + 4 = (-4/3)x + 8/3
y = (-4/3)x + 8/3 - 4
y = (-4/3)x + 8/3 - 12/3
y = (-4/3)x - 4/3