Question 830206
A man alternates between jogging and walking while exercising. He traveled 15 miles during the past 3 hours. He jogs at a rate of 7.5mph and walks and a rate of 4mph. How much time, to the nearest hundredth of an hour, did he spend walking and how much time did he spend jogging. 
I set it up like this:
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J+W=3
7.5J+4W=15
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Modify:
4J + 4W = 12
7.5J+4W = 15
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Subtract to get:
3.5J = 3
J = 6/7 hrs (time spent jogging)
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Solve for "W":
J + W = 3
(6/7) + W = (21/7)
W = 15/7 hrs (time spent walking)
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Cheers,
Stan H.
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