========================================================
Explanation:
We have these points
Focus on the x coordinates for now.
The x coordinates of A and B are -3 and x in that order. Add them up and divide in half to get the x coordinate of the midpoint M
(-3+x)/2 = 1
-3+x = 2*1
-3+x = 2
x = 2+3
x = 5
Repeat for the y coordinates
(6+y)/2 = 2
6+y = 2*2
6+y = 4
y = 4-6
y = -2
Therefore, the location of point B is (5, -2)
You can use a tool like GeoGebra to check your work.