Plz answer me i want help

Rs 19.20

Step-by-step explanation:

Buying price = Rs 20

Profit = 20% = 0.20 × 20 = Rs 4

Selling price = buying price + profit = Rs 20 + Rs 4 = Rs 24

He wants to make a 25% profit.

Let's say he should buy the pen at Rs 'a' in order to make that amount of profit.

∴ a + = 24

1.25a = 24

a =

So he should buy the pen at Rs 19.20

what is the original number? you forgot to add it.