Question

The perimeter of a rectangle is 240cm.
If it's length is decreased by 10% and breadth is increased by 20% we get the same perimeter.Find the original length and breadth of the rectangle

Answer 1

Answer:

given,perimeter of rectangle=140cm.

let length of rectangle is length and breadth is b.

perimeter of rectangle =2 (length +breadth)

240 cm=2 (l+b)

or, 120=l+b

l+b=120......(1)

a/c to question,

length decreased by 10%.

so,new length of rectangle is increased by 20%

so,new breadth of rectangle=b+20%.b=b+20B/100=12 Breadth

now,new perimeter of rectangle=2 (0.9 length +1.2 breadth )

but according to question,

intial perimeter of rectangle =final

so,240=2 (0.9 length +1.2 breadth)

0.9 length +1.2 breadth =120 .

.....(2)

from equation (1) and( 2), multiplying 5 with equation (2)-6 with equation (1).

5 (0.9 length +1.2 breadth)-6 (l+b)=5×120-6 ×120

4.5 l-6 l=-120

-15 l=-120

• length =80m and breadth =120 -l =40m

hence , length of rectangle =80

breadth of rectangle =40m

Step-by-step explanation:

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