A sales man offers the following scheme discount on the sale of pencils in his shop: 'Buy 20 and get 5 free'. What is the percentage of his scheme discount?

Correct option is C

Given:
A salesman offers a scheme: "Buy 20 and get 5 free."
Formula Used:
​$$\text{Percentage Discount} = \left( \frac{\text{Discounted Value}}{\text{Original Price}} \right) \times 100$$​​
Where the "Discounted Value" is the number of pencils received for free, and the "Original Price" is the price of the 25 pencils if no discount was applied.
Solution:
Number of free pencils = 5
Original number of pencils = 25
Percentage Discount = $$\frac 5{25} \times 100$$​ = 20%
Thus, the salesman is offering a 20% discount.