Correct Answer - Option 3 : 20%

**Given****∶**

A shopkeeper starts an offer “Buy 4 Get 1 free”.

**Formula Used****∶**

Discount = Marked Price – Selling Price

Discount % = Discount / Marked Price × 100

**Calculation****∶**

Let the price of 1 article be x

Total quantity = 4 + 1 = 5

Number of articles buy = 4

Marked price of 5 article = 5x

SP of 4 article = 4x

Discount = M.P – S.P = 5x – 4x = x

Discount % = (Discount / M.P.) × 100 = (x / 5x) × 100 = 20 %

**∴ The net percentage of discount is 20%.**