Profit from selling rice:

Selling price = Rs 30
Cost price = Rs 20

To calculate the profit, we need to use the formula:
Profit = Selling price - Cost price

Profit = Rs 30 - Rs 20
Profit = Rs 10

Therefore, the profit from selling rice is Rs 10.

Explanation:

The food seller earns a profit of Rs 10 for every kilogram of rice he sells. This means that for every kilogram of rice he buys for Rs 20, he sells it for Rs 30, earning a profit of Rs 10.

Profit is the difference between the selling price and cost price. In this case, the selling price is Rs 30 and the cost price is Rs 20. Therefore, the profit earned by the food seller is Rs 10.

Importance of profit:

Profit is an important measure of the success of a business. It indicates that the business is generating more revenue than it is spending on its operations. Profit allows the business to reinvest in its operations, expand its offerings, and provide better services to its customers.

In the case of the food seller, the profit earned from selling rice allows him to purchase more rice, expand his business, and provide better service to his customers.

Conclusion:

Profit is an important measure of the success of a business. The food seller earns a profit of Rs 10 for every kilogram of rice he sells. This profit allows him to reinvest in his business, expand his offerings, and provide better service to his customers.