SOLUTION: A driver travels 10 miles to work at a constant speed and travels the same distance home at a constant speed. His speed on the return trip was fifteen miles per hour faster, and th

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Question 401154: A driver travels 10 miles to work at a constant speed and travels the same distance home at a constant speed. His speed on the return trip was fifteen miles per hour faster, and the total time for both trips was one hour. Find his speed on the way to work.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A driver travels 10 miles to work at a constant speed and travels the same distance home at a constant speed. His speed on the return trip was fifteen miles per hour faster, and the total time for both trips was one hour. Find his speed on the way to work.
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To work DATA:
distance = 10 miles ; rate = x mph ; time = d/r = 10/x hrs.
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From work DATA:
distance= 10 miles; rate = x+15 mph ; time = d/r = 10/(x+15) hrs
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Equation:
time + time = 1 hr.
10/x + 10/(x+15) = 1
Multiply thru by x(x+15) to get:
10(x+15) + 10x = x(x+15)
20x+150 = x^2+15x
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x^2-5x-150 = 0
(x-15)(x+10) = 0
Positive solution:
x = 15
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Cheers,
Stan H.
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