The perimeters of 2 squares are 40cm and 32cm. Find the perimeter of a third square whose area is equal to the difference of the areas of the two squares?	Choose one
A) 20 cm
B) 24 cm
C) 32 cm
D) 28 cm
E) 30 cm

Rationale: "side of the 1 st square = 40 / 4 = 10 cm side of the 2 nd square = 32 / 4 = 8 cm area of the 3 rd square = 10 ^ 2 - 8 ^ 2 = 36 cm ^ 2 side of the 3 rd square = 6 cm required perimeter = 6 * 4 = 24 cm answer is b"
Answer: B