Question 385384: Nick drove 24 miles, one way, to deliver a pakage. On his way home he drove 20 miles per hour faster than he did on his way to deliver the pakage. If the total driving time was 1 hour for the entire trip, find nick's driving speed on the way home.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Nick drove 24 miles, one way, to deliver a pakage. On his way home he drove 20 miles per hour faster than he did on his way to deliver the pakage. If the total driving time was 1 hour for the entire trip, find nick's driving speed on the way home.
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Going-DATA:
distance = 24 miles ; rate = x mph ; time = 24/x hrs.
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Coming DATA:
distance = 24 miles ; rate = x+20 mph ; time = 24/(x+20) hrs
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Equation:
time + time = 1 hr
24/x + 24/(x+20) = 1
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24x+24*20 + 24x = x(x+20)
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x^2 + 20x = 48x + 480
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x^2 - 28x - 480 = 0
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Factor:
(x+12)(x-40) = 0
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Going-rate = 40 mph
Coming-rate = 60 mph
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Cheers,
Stan H.
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