a ball is thown upward from the top of the cliff 12 m at a velocity of 2.8 m/s. find maximum height and when it is attained; time it reached the ground

v = 2.8 - 9.8 t

v = 0 at top
so
t = .286 seconds rising

at top
h = 12 + 2.8 (.286) - 4.9 (.286)^2
= 12.4 meters

how long to fall from 12.4 ?
0 = 12.4 - 4.9 t^2
t = 1.59 seconds to fall from up there
so
total time = .286+1.59 = 1.88 seconds