Calculate the 2021 tax liability and the tax or refund due for each situation:

a. Mark is single with no dependents and has a taxable income of $60,000. He has $9,200 withheld from his salary for the year.

b. Harry and Linda are married filing jointly and have taxable income of $60,000. Harry has $4,250 withheld from his salary. Linda makes estimated tax payments totaling $3,000.

c. Aspra is single. His 20-year-old son, Calvin, lives with him throughout the year. Calvin pays for less than one-half of his support and his earned income for the year is $3,000. Aspra pays all costs of maintaining the household. His taxable income is $60,000. Aspra's withholdings total $7,800.

d. Randy and Raina are married. Because of marital discord, they are not living together at the end of the year, although they are not legally separated or divorced. Randy's taxable income is $25,000, and Raina's is $60,000. Randy makes estimated tax payments of $3,500, and Raina has $7,500 in tax withheld from her salary.