Suppose you live in the hypothetical country of Evergreen. Evergreen does not tax the first $10,000 of income, but imposes a tax of 10% on the next $30,000 of income, 20% on the following $60,000, and a top rate of 30% on any income above $100,000.

a. Suppose your income is $20,000. What is your marginal tax rate? What is your average tax rate?

b. Further suppose your neighbor's income is $50,000. What is her marginal tax rate? What is her average tax rate?

c. Is Evergreen's tax structure progressive, proportional, or regressive?