Please help :) it’s math

Aball is thrown from a height of 139 feet with an initial downward velocity of 15 ft/s. the ball's height h (in feet) after t seconds is given by the following. h=139-15t-16t^2 how long after the ball is thrown does it hit the ground? round your answer(s) to the nearest hundredth. (if there is more than one answer, use the "or" button.) t =

0if x and y vary inversely and y=6 as x=7, what is the constant of variation?

Write the equation in general quadratic form: plz !