The midpoint will be the point that is exactly between the two points given. This means that the horizontal distance from both points to the midpoint will be the same. Likewise for the vertical distance.
The horizontal distance between (-8,5) and (-1,-9) is
And the vertical distance is
Now, the midpoint will be located half the vertical distance and half the horizontal distance from the endpoints
Therefore, the x coordinate of the midpoint is
And the y coordinate is
Hence, the coordinates of the endpoints are