The coordinates of the midpoint:
[tex](\frac{x_1+x_2}{2}, \frac{y_1+y_2}{2})[/tex]
(x₁,y₁) - the coordinates of one endpoint
(x₂,y₂) - the coordinates of the other endpoint
The midpoint is (14,26).
One endpoint is A(32,40).
The other endpoint is B.
The x-coordinate of B:
[tex]\frac{32+x}{2}=14 \ \ \ |\times 2 \\
32+x=28 \ \ \ |-32 \\
x=-4[/tex]
The y-coordinate of B:
[tex]\frac{40+y}{2}=26 \ \ \ |\times 2 \\
40+y=52 \ \ \ |-40 \\
y=12[/tex]
The coordinates of B are (-4,12) - the answer is C.