Question

A dealer sells a toy for ₹ 24 and gains as much percent as the cost price of the toy. Find the cost price of the toy.

Answer 1

Selling price (S.P.) of the toy = ₹ 24

Let the cost price (C.P.) of the toy be ₹ x.

∴ Gain% = x%

Gain% = `("S.P." - "C.P.")/"C.P." xx 100`

∴ x = `(24 - "x")/"x" xx 100`

∴ x² = (24 – x)100 

∴ x² = 2400 – 100x

∴ x² + 100x – 2400 = 0

∴ x² + 120x – 20x – 2400 = 0

∴ x(x + 120) – 20(x + 120) = 0

∴ (x + 120) (x – 20) = 0

∴ x + 120 = 0 or x – 20 = 0

∴ x = – 120 or x = 20

But, the cost price cannot be negative.

∴ x = 20

∴ The cost price of the toy is ₹ 20.