SOLUTION: Roland made a trip of 450 miles in 8 hours. Before noon he averaged 60mph, and afternoon he averaged 50mph. At what time did he begin his trip and when did he end it?

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Question 164514: Roland made a trip of 450 miles in 8 hours. Before noon he averaged 60mph, and afternoon he averaged 50mph. At what time did he begin his trip and when did he end it?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let A be the number of hours he drove before noon.
Let B be the number of hours he drove after noon.
Total hours driven,
1.A%2BB=8
Total distance driven (Rate x Time = Distance)
2.60%2AA%2B50%2AB=450
Use eq. 1 to come up with A as a function of B.
1.A%2BB=8
A=8-B
Substitute this expression into eq. 2 and solve for B.
2.60%2AA%2B50%2AB=450
60%2A%288-B%29%2B50%2AB=450
480-60B%2B50B=450
-10B=-30
B=3
From eq. 1,
A=8-B
A=8-3
A=5
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He started the trip at 7AM and ended the trip at 3PM.