5. Two rectangles of dimensions $8 \mathrm{~cm}$ by $10 \mathrm{~cm}$ and $9 \mathrm{~cm}$ by $12 \mathrm{~cm}$ overlap as shown in the diagram. The area of the black region is $37 \mathrm{~cm}^{2}$. What is the area of the grey region?
A $60 \mathrm{~cm}^{2}$
B $62 \mathrm{~cm}^{2}$
C $62.5 \mathrm{~cm}^{2}$
D $64 \mathrm{~cm}^{2}$
E $65 \mathrm{~cm}^{2}$
5. E The areas of the two rectangles are $(8 \times 10) \mathrm{cm}^{2}=80 \mathrm{~cm}^{2}$ and $(9 \times 12) \mathrm{cm}^{2}=108 \mathrm{~cm}^{2}$. Since the area of the black region is $37 \mathrm{~cm}^{2}$, the area of the unshaded region is $(80-37) \mathrm{cm}^{2}=43 \mathrm{~cm}^{2}$. Hence the area of the grey region is $(108-43) \mathrm{cm}^{2}=65 \mathrm{~cm}^{2}$.