Convex quadrilateral $ABCD$ has $AB = 9$ and $CD = 12$. Diagonals $AC$ and $BD$ intersect at $E$, $AC = 14$, and $\triangle AED$ and $\triangle BEC$ have equal areas. What is $AE$? $\textbf{(A)}\ \frac {9}{2}\qquad$ $ \textbf{(B)}\ \frac {50}{11}\qquad$ $ \textbf{(C)}\ \frac {21}{4}\qquad$ $ \textbf{(D)}\ \frac {17}{3}\qquad$ $ \textbf{(E)}\ 6$