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 the breadth of the both the rectangles

Answer 1

Step-by-step explanation:

Suppose l and b be the length and breadth of the rectangle respectively.

So perimeter of rectangle = 2(l+b) = 240 cm

⇒(l+b) = 120......(i)

when length is decreased by 10%, then new length = l−l×10100 = 9l10

And when breadth is increased by 20%, then new breadth = b+b×20100 = 6b5

So, according to the question we have;

Perimeter = 2[9l10+6b5] = 240 cm

⇒2[9l+12b10] = 240⇒9l+12b = 240×102⇒3(3l+4b) = 1200⇒3l+4b = 400 ......(ii)

Now multiplying (i) by 3 and subtract (ii) from (i) we get;

3l+3b−3l−4b = 360−400⇒−b = −40⇒b = 40

Putting b = 40 in (i) we get;

l = 120−40 = 80

Therefore length and breadth of rectangle are 80 cm and 40 cm respectively.

Answer 2

Answer:

answer is length equals to 80 cm and breadth is 40 cm of first one and length equals to 72cm and breadth is 48 cm of second one

Step-by-step explanation:

this is the answer of this question