AHSME 1979 Problem 3

In the adjoining figure, $ABCD$ is a square, $ABE$ is an equilateral triangle and point $E$ is outside square $ABCD$. What is the measure of $\measuredangle AED$ in degrees? $\textbf{(A) }10 \textbf{(B) }12.5 \textbf{(C) }15 \textbf{(D) }20 \textbf{(E) }25$