SOLUTION: Tom Quig traveled 280 miles east of St. Louis. For most of the trip he averaged 60 mph, but for one period of time he was slowed to 10 mph due to a major accident. If the total tim

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Question 115520: Tom Quig traveled 280 miles east of St. Louis. For most of the trip he averaged 60 mph, but for one period of time he was slowed to 10 mph due to a major accident. If the total time of travel was 8 hours, how many miles did he drive at the reduced speed?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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Tom Quig traveled 280 miles east of St. Louis. For most of the trip he averaged 60 mph, but for one period of time he was slowed to 10 mph due to a major accident. If the total time of travel was 8 hours, how many miles did he drive at the reduced speed?
:
Let x = miles traveled at 20 mph
Then
(280-x) = miles traveled at 60 mph
:
Write a time equation: Time = Distance/speed
:
20 mph time + 60 mph time = 8 hrs
x%2F20 + %28%28280+-+x%29%29%2F60 = 8
:
Get rid of the denominators multiply by 60:
60*x%2F20 + 60*%28%28280+-+x%29%29%2F60 = 60(8)
:
Cancel out the denominators and you have:
3x + (280-x) = 480
:
3x + 280 - x = 480
:
3x - x = 480 - 280
:
2x = 200
:
x = 200/2
:
x = 100 mi at 20 mph
:
:
Check solution by finding the total time. (180 mi at 60 mph}
100/20 + 180/60 =
5 + 3 = 8; confirms our solution
:
You can also check it by finding the distance
20(5) + 60(3) =
100 + 180 = 280