The figure, not drawn to scale, is made up of two identical squares, A and C and a rectangle B. The ratio of the area A to the area of B to the area of C is 1 : 2 : 1. The ratio of the unshaded part of A to the unshaded part of C is 3 : 4 respectively. Given that half of the area of A is shaded and the total area of all the shaded parts is 80 cm², what is the area of the whole figure?

A		B		C
1x6 = 6 u		2x6 = 12 u		1x6 = 6 u
Unshaded	Shaded	Unshaded	Shaded	Unshaded	Shaded
	3			4
1x3	1x3
3 u	3 u	7 u	5 u	4 u	2 u

Since half of the area of A is shaded, the other half of the area of A is unshaded.
Unshaded part of A : Shaded part of A
1 : 1

The unshaded part of A is the repeated identity.
LCM of 1 and 3 = 3

Area of A is the combined repeated identity.
LCM of 1 and 6 = 6

A : B : C
1 : 2 : 1
6 : 12 : 6

Shaded part of A : Shaded part of C
3 : 4

Total shaded area
= 3 u + 2 u
= 5 u

5 u = 80

1 u = 80 ÷ 5 = 16

Area of the whole figure
= 3 u + 12 u + 4 u
= 19 u
= 19 x 16 
= 304 cm²

Answer(s): 304 cm²