2+2 tell me the answer

Triangle xyz has vertices x(1,3), y(0,0)

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

Need showing work for this problem 56.25 ×25.80