In a particular classroom, a student who did not study scored 60 points on a test. if that student scored 90 points when studying for three hours, what is the rate of change of his score per hour studied?

Melanie is buying a bathing suit that costs 39.99. she is given a discount at the cash register of $6.00 when she scratched 15% off on a game piece for a store promotion. what will the sale price of melanie’s bathing suit be?