Given a square with area x, you can use the formula d = 1.4x2 to estimate the length of the diagonal of the square. Use the formula to estimate the length of the diagonal of a square with area 100 cm?

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