Physics education research, electronic materials, and the musings of Christopher Moore, Ph.D.

So I have been doing this homework for about 6 hours now. and majorly need some help. I already did part A but I can't figure out B. Any help would be great.

A ball is thrown vertically upward with a
speed of 27.7 m/s from a height of 2.1 m.
a) How long does it take to reach its highest
point? Answer in units of s.
Answer: 2.826530612 Seconds
b) How long does the ball take to hit the
ground after it reaches its highest point? An-
swer in units of s.