2002 Pascal Problem 9

A rectangle is divided into four smaller rectangles. The areas of three of these rectangles are 6, 15 and 25, as shown. The area of the shaded rectangle is

\textbf{(A)}\ 7\quad \textbf{(B)}\ 15\quad \textbf{(C)}\ 12\quad \textbf{(D)}\ 16\quad \textbf{(E)}\ 10

If there are no answer choices shown, enter a numerical answer.

Full credit to this problem is given to the CEMC, you may view all Pascal contests here.