Question

the perimeter of a rectangle is 240 cm. if its length is increased by 10% and its breadth is decreased by 20% we get the same perimeter. find the length and the breadth of the rectangle.

Answer 1

Perimeter=240cm=2(L+B)
=240/2=L+B
=120=L+B
:.L=120-B.........(1)
ATQ-
2(L+10%×L+B-20%×B)=240
2(110/ L+80/ B)=240
2(11/10L+4/5B)=240
11/10L+4/5B=240/2
11/10L+4/5B=120
PUTTING VALUE of (1)
(11/10)(120-B)+(4/5B)=120
132-11/10B+4/5B=120
132-11/10B+8/10B=120
132-3/10B=120
-3/10B=120-132
-3/10B=-12
B=-12×-10/3
B=40cm............(2)
PUTTING VALUE in (1)
L=120-40
L=80cm
(ANSWER)
L=80cm
B=40cm

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