Gilbert and Brian drove 604 miles in 11.6 hours. Gilbert drove the first part of the trip and averaged 45 miles per hour. Brian drove the remainder of the trip and averaged 65 miles per hour. For what length of the time did Gilbert drive?
Let the time Gilbert spent driving =T The time Brian spent driving =11.6 - T
45T + 65(11.6 - T) =604, solve for T T = 7.5 hours that Gilbert spent driving. 11.6 - 7.5 =4.1 hours that Brian spent driving.