Answer:
(3,0)
Explanation:
To answer this, just find what was added to A to get to the midpoint, then add that to the midpoint for B.
So first, find how to get from (-1,3) to (1,2). If you add together -1 + 2, the answer is 1, the x value of the midpoint. If you subtract 3 - 1, the answer is 2, the y value of the midpoint.
Now, we just apply these to the midpoint, which should get us to the coordinates of B.
1 + 2 = 3
2 - 2 = 0
(3,0)
So, the coordinates of B are (3,0).