SOLUTION: I can run 3 times faster than I can walk. One day I walked for 2 hours and ran for 30 mins. ​If I travelled 21.7 km, how fast can I walk. Use algebra to solve.

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Question 1024607: I can run 3 times faster than I can walk. One day I walked for 2 hours and ran for 30 mins.
​If I travelled 21.7 km, how fast can I walk. Use algebra to solve.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
I can run 3 times faster than I can walk. One day I walked for 2 hours and ran for 30 mins.
​If I traveled 21.7 km, how fast can I walk. Use algebra to solve.
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Walk DATA:
distance = x km ; rate = r kph; time = x/r hrs
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Run DATA::
distance = 21.7-x km ; rate = 3r kph ; time = (21.7-x)/(3r) hrs
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Equations:
x/r = 2
(21.7-x)/(3r) = 0.5
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Substitute for "x" and solve for "r"::
(21.7-2r)/(3r) = 1/2
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3r = 43.4 - 4r
7r = 43.4
walk rate = 6.2 km/hr
run rate = 3(6.2) = 18.6 km/hr
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Cheers,
Stan H.
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