SOLUTION: the average rate of a bus is 15 miles per hour more than that of an average truck. the truck takes 1 hour more than th bus to drive 90 miles, how long does it take the bus
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Question 768713: the average rate of a bus is 15 miles per hour more than that of an average truck. the truck takes 1 hour more than th bus to drive 90 miles, how long does it take the bus Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! the average rate of a bus is 15 miles per hour more than that of an average truck. the truck takes 1 hour more than the bus to drive 90 miles, how long does it take the bus
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Bus DATA:
distance = 90 miles ; rate = r+15 mph ; time = 90/(r+15) hrs.
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Truck DATA:
distance = 90 miles ; rate = r mph ; time = 90/r hrs.
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Equation:
truck tme - bus time = 1 hour
90/r - 90/(r+15) = 1
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90(r+15) - 90r = r^2+15r
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r^2 + 15r - 1350 = 0
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(r-30)(r+45) = 0
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Positive solution:
r = 30 mph (truck speed)
r+15 = 45 mph (bus speed)
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Cheers,
Stan H.
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