SOLUTION: A farmer drives a tractor from one town to another a distance of 120 kilometers. He drives 10 kilometers per hour faster on the return trip, cutting 1 hour off the time. How fast
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Question 211161: A farmer drives a tractor from one town to another a distance of 120 kilometers. He drives 10 kilometers per hour faster on the return trip, cutting 1 hour off the time. How fast does he drive each way? Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! A farmer drives a tractor from one town to another a distance of 120 kilometers. He drives 10 kilometers per hour faster on the return trip, cutting 1 hour off the time. How fast does he drive each way?
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1st trip DATA:
distance = 120 km ; rate = x km/hr ; time = d/r = 120/x hrs
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Return trip DATA:
distance = 120 km ; rate = x+10 km/hr ; rime = d/r = 120/(x+10) hrs
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Equation:
1st trip time - return trip time = 1 hr
120/x - 120/(x+10) = 1
120x + 1200 - 120x = x(x+10)
1200 = x^2+10x
x^2 + 10x - 1200 = 0
(x+40)(x-30) = 0
Positive solution:
x = 30 km/hr (rate on the 1st trip)
x+10 = 40 km/hr (rate on the return trip)
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Cheers,
Stan H.
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