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 length and perimeter of the rectangle

Answer 1

HEYA !!

I'm doing this question using only one variable,

(given) Perimeter = 240 cm

so, let length be l .

now,

            2 ( l + b ) = 240

             l +b = 240/2

             l + b = 120

so, breadth be,

             b = 120- l

             according to the question,

        new  length =    l - 10% = 9/10l

        new breadth =   b+20% = 6/5b

A.T.Q,

2(l+b)=240

2(9/10l + 6/5b) = 240

9/10l + 6/5b = 240/2

9/10l + 6/5b= 120

(9l+12b)/10 = 120

9l + 12b = 120 × 10

9l + 12b = 1200

9l + 12( 120- l ) = 1200

9l  + 1440 - 12l = 1200

3l =  1440-1200

3l = 240

l = 80 cm

so, length is 80cm and breadth is 120-80 = 40cm.

hope it helps!!!