I would think virtually all business men and women know the difference between gross and net income. And I would count Donald Trump as one of these businessmen. But the NY Times claims that he sometimes confuses the two.
The Times has studied some of his financial disclosure forms and compared them with his appeals re property taxes. It concludes that on the disclosure forms he counts gross revenue with no offset for expenses. On the appeals he includes both revenue and expenses. An example: He reported $50,000,000 of revenue for Mar a Lago in 2014 but in his appeal of property taxes he also reported expenses of $52,400,000, or a loss of $2,400,000. There are other examples in the article.