You're given gross income of $53,350. This is the total the linguist made for the year. Federal income tax is what gets taken by the government, and since we're given the percentage that's docked the linguist's pay, we can calculate the dollar amount of federal income tax withheld.
Remember that you can convert 17.9% to decimal form, which is 0.179.
Multiply 0.179 by $53,350, and that will be the amount of federal income tax withheld. Hope that helps.
