The perimeters of 2 squares are 60cm and 48cm. Find the perimeter of a third square whose area is equal to the difference of the areas of the two squares? Select the correct option:
A) 20 cm  B) 28 cm  C) 36 cm  D) 48 cm  E) 40 cm

Rationale: side of the 1 st square = 60 / 4 = 15 cm side of the 2 nd square = 48 / 4 = 12 cm area of the 3 rd square = 15 ^ 2 - 12 ^ 2 = 81 cm ^ 2 side of the 3 rd square = 9 cm required perimeter = 9 * 4 = 36 cm answer is c
Answer: C