25. In the diagram below, $D$ and $E$ lie on the side $A B$, and $F$ lies on the side $A C$ such that $D A=D F=D E, B E=E F$ and $B F=B C$. It is given that $\angle A B C=2 \angle A C B$. Find $x$, where $\angle B F D=x^{\circ}$.
25. Answer: 108 .
Since $D A=D E=D F, \angle E F A=90^{\circ}$. Let $\angle E B F=\angle E F B=x^{\circ}$. Then $\angle B \dot{C} F=$ $\angle B F C=90^{\circ}-x^{\circ}$ and $\angle C B F=2 x^{\circ}, \angle B A C=90^{\circ}-2 x^{\circ}$.

It is given that $3 x=2(90-x)$. Then $x=36$. So $x=180-(90-x)-(90-2 x)=3 x=108$.