Question 336970
Sarah walks north at the rate of 3mph and returns at the rate of 4mph. how many miles did she walk if the round trip took 3.5hours?
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North DATA:
rate = 3 mph ; time = x hrs ; distance = rt = 3x miles
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Return DATA:
rate = 4 mph ; time = 3.5-x hrs ; distance = rt = 4(3.5-x) miles
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Equation:
distance = distance
3x = 4(3.5-x)
3x = 14-4x
7x = 14 
x = 2 hrs (North time)
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North distance = 3x = 3*2 = 6 miles
Return distance = 4(3.5-2) = 6 miles
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Round-trip = 6 miles
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Cheers,
Stan H.