Question

The length of a rectangle is decreased by r%, and the breadth is increased by
(r + 5)%. Find r, if the area of the rectangle is unaltered
​

Answer 1

Answer:

Let original length = x and original breadth = y

Then,

Original area = xy

New area :

=[(100−r)100×x][(105+r)100×y]=[(10500−5r−r210000)xy]∴(10500−5r−r210000)xy=xy⇒r2+5r−500=0⇒(r+25)(r−20)=0⇒r=20

so option D.20

Step-by-step explanation:

pls MARK BRAINLIEST