Final answer:
Operating revenues and non-operating revenues are the two ways to classify revenues and estimated revenues in business.
Step-by-step explanation:
There are two ways to classify revenues and estimated revenues: operating revenues and non-operating revenues. Operating revenues are generated from the primary activities of a business, such as sales of goods and services. Non-operating revenues, on the other hand, are generated from secondary activities, such as interest income or gains from the sale of assets.