heres the question

A rock is thrown vertically from the ground with a velocity of 24 meters per second and it reaches a height of 2+24t-4.9t(Squared) after t seconds. How many seconds after the rock is thrown will it reach maximum height and what is the maximum height the rock will reach in meters? how many seonds after the rock is thrown will it hit the ground? Round your answers to the nearest hundredth

Please help!!! I've tried everything and couldn't figure it out!!!