Answer:
8 hours.
Explanation:
Let t hours represent duration of entire race.
We have been given that Rachel finished 
 of the race in 6 hours. We are asked to find the duration of entire race.
 of the race in 6 hours. We are asked to find the duration of entire race.
As Rachel finished 
 of the race in 6 hours, so
 of the race in 6 hours, so 
 of x will be equal to 6.
 of x will be equal to 6.





Therefore, the duration of entire race was 8 hours.