best economy class Under the theoretical framework of the theory, the theory of commodity market equilibrium and the monetary market equilibrium of Keynesian theory are unified. Marx's theory of interest rate decisions from the perspective of the source and essence of interest, taking into account the institutional factors in the role of interest rate decisions of interest theory, its theoretical core is the interest rate is determined by the average profit margin. Marx believed that under capitalism, interest is a part of profit and a form of conversion of surplus value. relied on spending cuts to reduce the deficit, adding that it should be seen as part of further measures. It can be seen that shares and shares are the relationship between form and content and cannot be confused. As hicks income concept did not specify what is called "equal wealth", and thus the income concept formed the basis of many debates concept, and the theory of accounting earnings, especially the capital preservation theory has a great influence. In accounting, people used to call "maintaining the same level of affluence" as capital preservation. No one is a fool, and money doesn't make a profit. Yu 'ebao's interest rate cut is also to avoid risk. In his theory, money supply is controlled by the central bank and is an exogenous variable with no interest rate elasticity. At this point, monetary demand depends on people's psychological "liquidity preference". The American petroleum institute (API) released data showing a decline in U.S. crude oil and refined refining inventories, while gasoline inventories rose.