Question 108849
Gilbert and Chris drove a total of 1040 miles in 17.4 hours. Gilbert drove the first part of the trip and averaged 55 miles per hour. Chris drove the remainder of the trip and averaged 65 miles per hour. For what length of the time did Gilbert drive?
:
Let t = time that G drove
Then
(17.4 - t) time that C drove
:
It gives us the total miles driven, write a distance equation:
Distance = Speed * time
:
C's dist + G's dist = 1040 mi
65(17.4-t) + 55t = 1040
:
1131 - 65t + 55t = 1040
:
-10t = 1040 - 1131
:
-10t = -91
:
t = -91/-10
:
t = + 9.1 hrs driven by G
:
:
Check solution, by confirming the distance
::
C drove: 17.4 - 9.1 = 8.3 hrs
:
(65*8.3) + 55*9.1) =
539.5 + 500.5 = 1040
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