Eric plans to rent a car for a day from Easy Car Rental. He has a coupon for 25% off the daily base rate of $40. He will also have to pay an additional $0.15 for each mile he drives. Which expression represents the situation? (m represents the number of miles)

In this situation, there are 2 separate terms (parts of the story).  The first part is the information about the coupon that applies to the daily rate of $40.  You will represent this as 0.75 (for the 75% that you will be paying) x 40.  (The other part of this story is that you are paying $0.15 per mile which is represented as 0.15m.  You need to put these together to get 0.75(40) + 0.15m.  The 0.25 times 40 can be simplified to say 30, so write it as $30 + $0.15m.