Apples beans rats tomatoes

Which of the following is the true for f(x) = 5cos

Solve 3x-18=2y and 5x-6y=14 by elimination or substitution . show all !

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