Good morning! I missed two math classes and am trying to solve the exercises from the textbook and understand them. I will be glad for your help.

A batter hits a baseball with an intial speed of 80 feet per second. if the intial height of the ball is 3.5 feet above the ground, the function d(t)= 16t2 + 80t +3.5 models the ball's height above the ground in feet as function of time in seconds. how long will it take to reach the maximum height