PLEASE HELP!! WILL GIVE BRAINLIEST!!

An archer shoots an arrow into the sky where the motion of the arrow can be modeled by the equation:
f(t) = -16t² + 80t
where t is time in seconds and f(t) is height in feet.
Find how long it will take the arrow to hit the ground using an algebraic method
Show all of your reasoning/steps used with this algebraic method.​