Answer:
The coordinates of B are (-10,7).
Explanation:
The midpoint between two points is the mean of the coordinates of these two points.
In this question:
Point A(2,-1)
Point B(x,y)
Midpoint is (-4,3)
Finding coordinate x:
-4 = (2 + x)/2
2 + x = -8
x = -8 - 2
x = -10
Finding coordinate y:
3 = (-1 + y)/2
y - 1 = 6
y = 7
The coordinates of B are (-10,7).