profit and loss questions Modern economy, the interest rate as the price of money, not only restricted by many factors in the economic and social, and changes in interest rates to have a great impact on the economy as a whole, as a result, modern economists are studying the interest rate decision problem, pay special attention to the relationship between the variables and the balance of the economy as a whole, the interest rate decision theory has experienced the classical interest rate theory, Keynes's interest theory, interest rate in loanable funds theory and is-lm analysis as well as the contemporary evolution of dynamic interest rate model, the development process. Although interest rates are expected to rise further next year, savers should not expect higher interest rates from Banks, experts have suggested. At present, about the nature of the enterprise. Western economists have different views. There is also some debate. Some western economists analyze the nature of the enterprise mainly from the perspective of transaction costs that coase emphasizes. While many key factors need to be taken into account when making plans, the core issue always is when to exit the transactions that have been entered. This actually includes three exit plans. For one thing, there must be a plan to accept losses, and to pull out if the deal loses. Second, there must be a plan to accept a profit, and once the profit target is met, it will be satisfied. Third, there must be a plan that allows the trader to exit the transaction in the event that a significant change is not occurring for a considerable period of time.