Can outputs repeat in functions? i know inputs can’t, but can outputs?

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax

Eden has a part time job. she is paid ? 7.20 an hour the week she worked 18 and a half hours how much is she paid

Solve 2x − 1 = 11 for x using the change of base formula log base b of y equals log y over log b.