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? 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

Alright, lets get started.

Please refer the diagram I have attached.

Joyce rode her bicycle 4 miles from her house to the library.

Suppose the average speed of Joyce =  x miles per hours

She rode the same distance from the library to the gym means 4 miles.

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

So, the average speed from library to the gym will be = miles per hour

So this expression is same as (x-15), the expression Joyce modeled.

Hence (x-15) repreents Joyce's average speed from the library to the gym.

So option C is correct answer.   :   Answer

Hope it will help :)