a. What are the tax liability, the marginal tax rate, and the average tax rate for a married couple filing jointly with $68,900 taxable income?

b. What are the tax liability, the marginal tax rate, and the average tax rate for a single individual with $214,200 taxable income?

c. What are the tax liability, the marginal tax rate, and the average tax rate for a head of household with $463,300 taxable income?