Miss Arkin owns a profitable sole proprietorship. Her filing status is single. For each of the following three cases compute her 2020 self- employment tax and any additional Medicare tax on earned income. Show your work.

a. Miss Arkins net profit from Schedule C was $64,000. She had no other income.

b. Miss Arkins net profit from Schedule C was $64,000, and she received a $90,000 salary from an employer. She has no other income.

c. Miss Arkins net profit from Schedule C was $ 14,000, and she received a $160,000 salary from an employer. She has no other income.