Question 10
In the diagram below, $ABC$ is a triangle with a right angle at $C$. Point $E$ is on $AC$ and point $D$ is on the extension of $CB$ such that triangle $DEC$ is similar to triangle $ABC$. If $AB$ cuts $DE$ at $F$, and $AE=EF$, then what is the measure, in degrees, of $\angle ABC$.
