Multiple choice

The length of a rectangle is thrice its breadth. If its length is increased by 4 cm and the breadth is decreased by 3 cm, the area of the rectangle is decreased by 77 cm2. Therefore, the length of the rectangle is

  1. 20 cm

  2. 30 cm

  3. 39 cm

  4. 40 cm

  5. 24 cm
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let breadth =x cm and length = 3x cm Then, original area = x*3x = 3x2 cm2, After changing into dimensions, Area = (3x + 4)*(x – 3) = 3x2 – 5x - 12 So, 3x2 – (3x2 – 5x – 12) = 77, 5x + 12 = 77 x = 13, Length = 3*13 = 39 cm.

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