Answer:
See below
Step-by-step explanation:
a = -16   =  - 1/2 a   where a is acceleration of gravity (32 ft/s^2)
b = 90   = initial velocity   90 ft/s
c = 0 Â Â Â = initial height = 0 ft ( kicked from off of the ground )
Height = 0 Â when the ball hit the ground
       0 = -16t^2 + 90t
        0 = -t ( 16t-90)    t = 0   or  90/16 = 5.63 seconds