Explain how each of the following will affect the net public debt, other things being equal.

a. Previously, the government operated with a balanced budget, but recently there has been a sudden increase in federal tax collections.

b. The federal government had been operating with a very small annual budget deficit until three successive hurricanes hit the Atlantic Coast, and now government spending has risen substantially.

c. The General National Mortgage Association, a federal government agency that purchases certain types of home mortgages, buys U.S. Treasury bonds from another government agency.