Can someone please help me on this question I don’t have much time thank you

How do you use the elimination method for this question? explain, because i really want to understand!

What is the rate of change of a line that passes through (2,-5) and (6,-2)?

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 =