Precalculus

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Rosea drives her car 30 kilometers to the train station, where she boards a train to complete her trip. The total trip is 120 kilometers. The average speed of the train is 20 kilometers per hour faster than that of the car. At what speed must she drive her car if the total time for the trip is less than 2.5 hours?

  • Precalculus -

    distance = velocity x time or
    time = distance / velocity
    total time=d1/v1+d2/v2=2.5 hrs (1)
    where d1 = car distance = 30 (2)
    v1 = car speed
    d2 = train distance = 120 - d1 (3)
    v2 = train velocity = v1+20 (4)
    combine (1), (2), (3), and (4) and solve for v1

  • elementary -

    300 and 200000

  • Precalculus -

    idk can you show me how please

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