Typical problem sets depend on the area of macroeconomics that you are studying and the opinion of your professor. You may be asked to calculate supply and demand curves, long-term growth rate, productivity, balance of payments or international trade. Based on the opinion of the professor, there may be different ideas of the effect of taxes on an economy. The safest idea is to use the principles from the book you are studying.
The principles of macroeconomics focus around national growth, debt, international trade and taxes. The most important number is the Gross Domestic Product (GDP), which is the sum of all the productivity in one country. It calculates the sum of private consumption, gross investment, government spending and exports minus imports. A typical problem set can give the components of this number and ask students to solve for the Gross Domestic Product.
Keynesian economics is one of the central ideas of macroeconomics. Formed by British economist John Maynard Keynes in the the 1920s and '30s, it posits that the government should smooth out the economic cycle by borrowing and spending heavily during times of recession. Keynes believed that the government was the "marginal" demand that could get the economy rolling after it begins its decline. He believed that the debt would then be paid off with the resulting economic boom from government spending. A typical problem set can examine the role of stimulus on an economy. For example, calculate the marginal return on government stimulus spending. A student uses the "natural growth" rate (assume 3 percent in the U.S., based on historical figures) and then find the difference after government stimulus spending.
Monetarism holds that the money supply should be kept in check and the government should refrain from extra spending during times of recession. Monetarists, most famously led by Richard Friedman in the 1970s, believe that recessions are good for eliminating unproductive business and assets so that better investments can be found. Monetarists believe in the private sector and can be summed up by the idea, attributed variously to Henry Thoreau and Thomas Jefferson, that "The government that governs best governs least." A typical problem examines the negative impact of taxes on the economy. Students take the "natural growth" of an economy and examine the difference in GDP after a tax hike.