Question 6
In rectangle $ABCD$, choose $E$ on $AB$. Points $M,N$ lie on $CE$ in the order $C,M,N,E$, with $CM=MN=NE$. The line $DN$ meets the side $AB$ at $F$, as shown. The total shaded area is $12\text{ cm}^2$. Find the area of rectangle $ABCD$ in square centimetres, explaining your reasoning.
