You want to use the data from a function to make a prediction.  Would a function generated by a mathematical rule or a function lacking a mathematical rule lead to a more accurate prediction?  Justify your answer

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