Find the other endpoint of the line segment with the given endpoint and mid point.

1. Endpoint:(-1, 9), midpoint: (-9, -10)
2. Endpoint: (2, 5), midpoint: (5, 1)
3. Endpoint:(9, -10), midpoint: (4, 8)
4. Find the point that is one-fourth of the way from (2, 4) to (10, 8).