When the money market is drawn with the value of money on the vertical axis, as the price level increases the quantity of money

A tax system in which the tax rate on everyone's first $10,000 of income is 10 percent, the tax rate on everyone's second $10,000 of income is 15 percent, and the tax rate on all income over $20,000 is 25 percent is a(n):

a. proportional tax. b. equitable tax. c. head tax. d. unit tax. e. progressive tax.

Which of the following statements is not correct?

a. Government policies may improve the market's allocation of resources when negative externalities are present. b. Government policies may improve the market's allocation of resources when positive externalities are present. c. A positive externality is an example of a market failure. d. Without government intervention, the market will tend to undersupply products that produce negative externalities.