Why cost and benefits is important?

Why do so many people work in the informal sector? What is the definition of underdeveloped economy? Reasons for existence of small business? Because corporations do not actually raise any funds in secondary markets they are less important to the economy than primary market? Cost of eggs in 1995? How does a production possibilities curve illustrate Opportunity costs? A barter economy is? Give limitation of decentralized economic planning? What economic problems confronted farmers in the 1890s? What is an economic side effect of a good or service that generates benefits or costs to someone other than the person deciding how much to produce or consume? In what year did national services come into being and finally end? What are the economic impacts of uranium nuclear fission? Why are economies never purely market or command economies? What is favorable balance of trade? How does fair trade help the community? What best describes a result of division of labor in early farming communities? Is maximized in the objective function by subtracting cost from revenue? How much is a hundred rupees in dollars? What is the value of a 20 us bill series of 1929 that says national currency on the top and stamped by the federal reserve bank of Minneapolis mn? What is the symbol of greed?