A dealer sells a toy for Rs.24 and gains as much percent as the cost price of the toy. Find the cost price of the toy.
Ans: Let the C.P be x
∴Gain = x%
⇒ Gain =x. x/100
S.P = C.P +Gain
SP = 24
x + x^{2}/100 =24
On solving x=20 or -120 (rej)
∴C.P of toy = Rs.20