Question 66943
This is an analytic geometry problem. With all geometry problems, it is wise to draw a neat, accurate diagram to help you solve the problem.

I'll let you draw the diagram yourself (in this case, you can even sketch it).

Remember that the midpoint formula:

Midpoint of a line = ( Average of the x and y coordinates)

                    = ( (x1 + x2)/2 , (y1 + y2)/2 )

Find the points on which the hypotenuse is situated and use this formula.