How are revenues calculated on an income statement?

"Revenues are the dollar amount of sales plus any other income received from sources such as interest, dividends, and rents. The revenues of Delicious Desserts arise from sales of its bakery products. Revenues are determined starting with gross sales, the total dollar amount of a company’s sales. Delicious Desserts had two deductions from gross sales. Sales discounts are price reductions given to customers that pay their bills early. For example, Delicious Desserts gives sales discounts to restaurants that buy in bulk and pay at delivery. Returns and allowances is the dollar amount of merchandise returned by customers because they didn’t like a product or because it was damaged or defective. Net sales is the amount left after deducting sales discounts and returns and allowances from gross sales. Delicious Desserts’ gross sales were reduced by $4,500, leaving net sales of $270,500."