(b) The fifth and twelve terms of an A. P. are respectively 17 and 45. Find the sum of the first 15 terms of the progression? it's a optional mathematics Questions please solve him​

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 =