Mathematics
A rectangle's length is 5 cm less than twice its width. If the length is decreased by 5 cm and width is increased by 2 cm, the perimeter of the resulting rectangle will be 74 cm. Find the length and the width of the original rectangle.
Linear Eqns One Variable
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Answer
Let the width of the rectangle be w cm
Length of the rectangle is 5 cm less than twice its width.
l = 2w - 5 cm
New width = old width + 2
= w + 2 cm
New length = old length - 5
= (2w - 5) - 5 cm
= 2w - 5 - 5 cm
= 2w - 10 cm
New perimeter = 2(new length + new width)
⇒ 2((2w - 10) + (w + 2)) = 74 cm
⇒ 2(2w - 10 + w + 2) = 74 cm
⇒ 2(3w - 8) = 74 cm
⇒ 6w - 16 = 74 cm
⇒ 6w = 74 + 16 cm
⇒ 6w = 90 cm
⇒ w = cm
⇒ w = 15 cm
Length = 2w - 5 cm
= 2 x 15 - 5 cm
= 30 - 5 cm
= 25 cm
Hence, the length is 25 cm and breadth is 15 cm.
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