How far away can a boy ride his bicycle if he rides away at

How far away can a boy ride his bicycle if he rides away at 10 kilometers per hour and returns at 9 kilometers per hour? The entire trip takes 9.5 hours.

Solution

You will need to apply the distance formula:
d = rt
where
d is distance
r is rate or speed
t is time
.
Let t = time going away
then
9.5-t = time returning
.
\"distance going away\" = \"distance returned\"
10t = 9(9.5-t)
10t = 85.5 - 9.5t
19.5t = 85.5
t = 85.5/19.5
t = 4.385 hours
.
To answer the question:
4.385 * 10 = 43.85 kilometers