calculation of economic profit Frances O 'grady, chief secretary of the UK federation of industry and industry, said: "this suggests that brexit uncertainty has damaged the household budget. Work and living standards must be a priority in determining the best choice for brexit. The government should maintain a single market membership at the negotiating table. " The principle of rational investment: investment in securities investment in analysis and comparison. In 2017, the blockchain enters the public eye through bifurcation, CryptoKitties and ICO. Driven by investment opportunities and media attention, traditional businesses and consumers have begun to focus on the cryptocurrency and its underlying blockchain technology. Rolling planning laws is according to the principle of "almost fine far" a certain period of the plan, then according to the plan implementation and environmental changes and adjustments and changes to the plans for the future, and by backward, combine short-term and medium-term plans of a kind of planning method. 6. The accounting benefit is bound by the prudent principle. According to the principle of prudence, when there are a variety of accounting methods to choose from an economic business of an enterprise, it should choose a method that neither overestimates nor depreciates the benefits. Enterprises manipulate profits to achieve homogenization of profits, most of which adopt the method of overestimating earnings, and the subjective selection of the period of value-added. In economic terms, the benefits of holding any two currencies should be equal in the equilibrium of the foreign exchange market, which is: Ri=Rj (interest rate parity). Here, R stands for yield, and I and j represent currencies of different countries. If the benefits of holding two currencies are unequal, you will have A arbitrage: buy A kind of foreign exchange and sell B foreign exchange. Time factor a transaction's expected time is a question worth considering.