Question 96532
21 minutes = 21/60 hours = 7/20 hours
2 hours 21 minutes = (2 + 7/20) = 47/20 hours


Let us suppose that Brian jogged for 't' hours.
So, he rode on bike for (47/20 - t) hours.


Distance = Speed x Time


The distance for which Brian jogged = 5t miles.
The distance for which Brian biked = 18(47/20 - t) = (42.3 - 18t) miles.
Therefore the total distance traveled = (42.3 - 13t) miles.
But this distance is equal to 34.5 miles.


So, 42.3 - 13t = 34.5
13t = 42.3 - 34.5 = 7.8
t = 7.8/13 = 0.6

So, he jogged for 0.6 hrs. i.e. for 36 minutes and biked for the rest (141 - 36 =) 105 mins i.e. 1 hr. 55 mins.