Question 12
A triangle is divided into seven triangles. Four of them have areas $420\ \mathrm{cm}^2$, $80\ \mathrm{cm}^2$, $60\ \mathrm{cm}^2$ and $30\ \mathrm{cm}^2$ as shown in the diagram below. Find the area, in $\mathrm{cm}^2$, of triangle $AEF$.
