【Question 20】
As shown, $A B C D$ is a square, and points $E$ and $F$ are the midpoints of sides $A B$ and $B C$, respectively. $D E$ and $D F$ intersect the diagonal $A C$ at points $M$ and $N$. If the area of square $A B C D$ is $48 \mathrm{~cm}^{2}$, find the area of pentagon $E B F N M$.