Question

The midpoint of segment PQ is (10, -3) and the coordinates of point P are (-9, 7). What are the coordinates of point Q?

Answer 1

The midpoint is the average of the two end points:

... M = (P + Q)/2

We can solve this for Q.

... 2M = P + Q

... Q = 2M - P

Filling in your values, we get

... Q = 2(10, -3) - (-9, 7) = (20-(-9), -6-7)

... Q = (29, -13)