Austerity and spending are very hot topics discussed by economists, politicians, and journalists. Unfortunately, there is no an agreement concerning proper fiscal and monetary policies to improve the economy. The book shows how to use the developed models to evaluate the dynamics of the debt to GDP ratio for the cases of government spending and tax cuts and make decision whether such economic measures are efficient. It also offers an approach to establish yearly goals to decrease a country's debt based on a long-term goal and balance its budget in a certain number of years. The book contains concrete examples related to the U.S. economy and computer programs used to solve these examples; these programs can be used to analyze the economies of other countries.