10. As shown in the figure, $ABCD$ is a square piece of paper. The paper is folded along $CE$, with point $D$ folding to point $G$. Then, the paper is folded along $CF$, with point $B$ folding to point $G$. If $DE=18$, $BF=6$, then the area of $\triangle AEF$ is $\qquad$ .
$108$