Economic profits (or loss) is defined as the difference between revenues and the opportunity cost forgone. In the current case, the entrepreneur opted to start a business rather than being employed.
Therefore;
Economic profit = Revenues - Opportunity cost
In this problem;
Revenues = $300,000 - $150,000 - $25,000 - $25,000 = $100,000
Opportunity cost = $75,000
Therefore;
Economic profit = $100,000 - $75,000 = $25,000