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The length of a rectangle is twice that of its breadth. The perimeter of a given rectangle is 90 cm. If the length decreased by 5 cm and breadth increased by 5 cm, then the area of the rectangle increased by how much (in sq. cm)?

Answer 1:

Lenght = 2b

Perimeter = 2(l=b) = 90

2 (2b=b) = 90

b=15 cm

Therefore, Area of the rectangle= 30*15 = 450 sq. cm

Length= 30 cm

New length = 30-5= 25 cm

New breadth = 15=5 = 20 cm

Therefore, new area = 25*20 = 500 sq. cm 

Hence increased area = (500-450) sq. com = 50 sq. cm