Joyce rode her bicycle 4 miles from her house to the library, and she rode th from the library to the gym was 15 miles per hour less than her average spe Joyce modeled the trip from her house to the gym with the following expression. What does X - 15 represent in this situation? A. Joyce's average speed from her house to the library B. the distance between the library and the gym C. Joyce's average speed from the library to the gym D. The total time taken from Joyce's house to the gym​