Question

Joyce rode her bicycle 4 miles from her house to the library, and she rode the same distance from the library to the gym. Her average speed from the library to the gym was 15 miles per hour less than her average speed from her house to the library. Joyce modeled the trip from her house to the gym with the following expression. What does x - 15 represent in this situation?

Answer 1

Call y the average speed from the library to the gym

Call x the average speed from the house to the library.

"Her average speed from the library to the gym was 15 miles per hour less than her average speed from her house to the library" => y = x - 15

So, x - 15 represents Joyces's average speed from her house to the libray to the gym.