Given:
A line segment with a midpoint = (4, 4)
The segment has the endpoints (1,2) and (a,b)
We will find the point (a, b) using the following formula:

Where M is the midpoint of the line segment PQ
So, we can write the following equation:

Solve for (a, b) as follows:

So, the answer will be (a,b) = (7,6)