Acceleration is the rate at which velocity changes.
Answer:
55 min
Explanation:
The missing question is: how long does the trip take?
First of all, we need to find the initial distance covered by Dylan. In the first part, he rides for

at a speed of
v = 15 mph
therefore, the distance he covered is

Then Dylan stopped for a time of

Finally, on the way back, Dylan covered again this distance but travelling at a new speed of
v = 10 mph
So, the time he took is

So, the total time of the trip was

They can do the experiment more than once and make sure they follow steps right like in a experiment