In 2019, Carson is claimed as a dependent on his parents' tax return. Carson's parents provided most of his support.

a. Carson is 17 years old at year-end and earned $14,000 from his summer job and part-time job after school. This was his only source of income.

b. Carson is 23 years old at year-end. He is a full-time student and earned $14,000 from his summer internship and part-time job. He also received $5,000 of qualified dividend income. (Do not round intermediate calculations. Round your answer to 2 decimal places.)

What is Carson's tax liability for the year in each of the following alternative circumstances? Use Tax Rate Schedule, Dividends and Capital Gains Tax Rates, Estates and Trusts for reference.