Trina has a credit card that uses the adjusted balance method. for the first 10
days of one of her 30-day billing cycles, her balance was $780. she then
made a purchase for $170, so her balance jumped to $950, and it remained
that amount for the next 10 days. trina then made a payment of $210, so her
balance for the last 10 days of the billing cycle was $740. if her credit card's
apr is 17%, which of these expressions could be used to calculate the
amount trina was charged in interest for the billing cycle?