A rectangle has the length doubled to its width. If the width is increased by 5 cm and the length is decreased by 5cm, then the new area is increased by 75 Sq. cm. Find the original length of the rectangle.
Option:
A. 40 cm
B. 60 cm
C. 80 cm
D. 120 cm
Answer: A . 40 cm
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Justification:
Original length of the rectange is L.
Original width of the rectange is B.
=> L = 2B.
Area A = L * B = 2 * B^2.
New area of the rectange N = (L-5) * (B+5) = A - 5B +5L - 25 = A + 75
=> 5 (L -B) = 100
=> 5 (2*B - B) = 100
=> B = 20
=> L = 40 cm
