A shopkeeper bought 80 kg of rice at a discount of 10%. Besides 1 kg rice was offered free to him on the purchase of every 20 kg rice. If he sells the rice at the marked price, his profit percentage will be:

Let the Price of 1 kg rice be Rs.1.

Total rice bought = 80 kg

He offered 1 kg rice free on the purchase of every 20 kg rice.

Free rice = 80/20 = 4 kg

Rate of 80 kg rice = Rs.80

Discount = 10%

Cost price of rice for shopkeeper = 80 $$\times \frac{90}{100}$$ = Rs.72

Selling price of rice for shopkeeper = 80 + 4 = Rs.84

Profit = 84 - 72 = Rs. 12

Profit percentage = $$\frac{12}{72} \times 100$$ = $$16 \frac{2}{3}$$%