Need help asap! The distance on a map is 3 centimeters. Find the actual distance if the scale on the map is 1 cm = 30 miles.

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