Remark
The midpoint of any line has a definite formula. All you need do is define the formula parts in terms of the points.
Formula
x = (x1 + x2)/2
y = (y1 + y2)/2
Givens
x1 = -2
x2 = 3
y1 = 2
y2 = -1
Solution
x = (-2+3)/2 = 1/2
y = (2 + -1)/2 = 1/2
Answer
The midpoint is (1/2,1/2)