math

The height h of an object projected upward from the floor of the Golden Gate Bridge which has an initial height of 220 feet and with an initial velocity of 30 feet per second is given by h=-16t^2+30t+220. How many seconds later will the rock hit the water? Round to the nearest tenth. Please help ASAP!!! :(

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  1. Assuming that the 200 feet is the height above the water,
    -16t^2+30t+220 = 0
    8t^2 - 15t - 110 = 0

    Use your favourite method of solving a quadratic, reject the
    negative answer.

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