Compute the additional Medicare tax for the following taxpayers. If required, round your answers to the nearest dollar.

a. Mario, who is single, earns wages of $440,000 in 2020. His additional Medicare tax is $

b. George and Shirley are married and file a joint return in 2020. During the year, George earns wages of $138,000, and Shirley earns wages of $210,000. Their additional Medicare tax is $

c. Simon has net investment income of $38,000 and MAGI of $223,000 and files as a single taxpayer. Simon's additional Medicare tax is $