A dealer sells an article for Rs. 24 and gains as much percent as the cost price of the article. Find the cost price of the article.

Explanation

Let, C.P. of article be RS.x
Then, gain =x%
`becauseS.P=(100+"gain%")/(100)xxC.P.(orS.P.=C.P+C.Pxx(x)/(100))`
`implies24=(100+x)/(100)xxx`
`implies2400=100x+x^(2)`
`impliesx^(2)+100x-2400=0`
`impliesx^(2)+120x-20x-2400=0`
`impliesx(x+120)-20(x+120)=0`
`implies(x-20)(x+120)=0`
`impliesx=20orx=-120`
`impliesx=20" "("C.P.cannot be negative")`
Hence, the cost of article is RS.20.