Correct Answer - Option 1 : Rs. 20

**Given **

The selling price of cap = Rs 24

**Formula Used **

Cost price = {Selling Price/(100 + profit%)} × 100

**Calculation **

Let the cost price be x

⇒ x = 24/(100 + x) × 100

⇒ x^{2} + 100x - 2400 = 0

⇒ x^{2} + 120x - 20x - 2400 = 0

⇒ x(x + 120) - 20(x + 120) =

⇒ (x - 20)( x + 120)

We get x = 20 and x = - 120

(As cost price cannot be negitive)

So, cost price = Rs 20

**∴ The cost price is Rs 20**