Emma doesn’t have experience using credit cards. in fact, she just got her first one. she is also about to start her first year of college. she uses her new credit card to purchase textbooks for her classes. the total comes to $300. these are the terms of her credit card: it has a 15% yearly interest rate. the interest is compounded monthly. the card has $0 minimum payments for the first four years it is active. the expression that models this situation is ,where represents the growth factor of the interest rate. part a identify the values of , , and in the expression based on the verbal description of the emma’s situation. then, substitute those values into the formula to form an expression in terms of time.