Since the x-coordinates are the same, the segment s vertical and the x-coordinate of the desired point
is also -1.
As we move along the segment from (-1, -8) to (-1,7), y increases by 15. Since 2+3=5, we are partitioning the segment into 5 equal sections each of which has length 15/5 = 3
So, the desired point is (-1, -8 + 2(3)) = (-1, -2)