Abcd is a parallelogram. a is the point (2,5), b is the point (8,8) and the diagonals intersect at (3.5, 2.5). what are the coordinates of c and d? how do i work this out?

Check the picture below.

so, we know that 3.5, 2.5 is the midpoint of each diagonal, keeping in mind that, in a parallelogram, the diagonals bisect each other, namely, they cut each other in two equal halves.

The answer is 49/16 or 3 1/16