formula of profit Based on the above two kinds of comparison and analysis of the concept of earnings, reveals the inadequacy of accounting earnings, i.e., the accounting income does not take into account inflation, the production gains, goodwill to improve the impact of changes and their value, and can be found on only the pursuit of reliability, and can be measured, which affect the enterprise's profit ability and continuous operation ability. Accounting, since the 1950 s began to pay attention to absorb the income concept of some reasonable kernel of economics, the concept of modern accounting theory of income in the income concept of economics. Interest rate Edwards and bell's point of view Ideally suited for a wide range of applications, the PURe® aluminium windows are available as tilt and turn or casement windows. Senior’s innovative door range also features a choice of the PURe® FOLD and PURe® SLIDE options. The investment quantity is the decreasing function of interest rate, saving is the increment function of interest rate, and the change of interest rate depends on the equilibrium point of investment quantity and saving amount. Keynes's theory of money supply and demand decided that interest rates were a monetary factor rather than an actual factor.