Consider an income tax with the following parameters.

In order to determine their taxable income (i.e., the portion of total income subject to taxation), all taxpayers are allowed to deduct $20,000 from their income. Taxable income between $0 and $150,000 is subject to a 30% tax rate. Taxable income in excess of $150,000 is not taxed. (If a person's taxable income is greater than $150,000, they still owe 30% tax on the first $150,000 of income; it is only the portion of taxable income in excess of $150,000 that is untaxed. For example, a person with $160,000 of taxable income owes 30% tax on the first $150,000 but does not owe tax on the remaining $10,000.)

a. What are the average and marginal tax rates for a person with $20,000 of total income?

b. What are the average and marginal tax rates for a person with $100,000 of total income? c. What are the average and marginal tax rates for a person with $500,000 of total income?

d. Is the tax progressive, proportional, or regressive with respect to income? Explain your answer.