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 $$375,800.$

His additional Medicare tax is $$\_\_\_\_$

b$.$ George and Shirley are married and file a joint return. During the year, George earns wages of $$239,200,$ and Shirley earns wages of $$358,800.$

Their additional Medicare tax is $$\_\_\_\_\_\_$

c$.$ Simon has net investment income of $$57,160$ and MAGI of $$285,800$ and files as a single taxpayer.

Simon's additional Medicare tax is $$\_\_\_\_\_\_$