Body dropped from X at t=0 s

Passes Y at t = T, therefore passes Z at t = T+2

Between Y and Z we have:

s=150 m, t=2.0 s, a=10 m/s2, u=?

s=ut+½at²

150=2u + ½x10x2²

u = 65 m/s     =>> T = 6.5 s

Thus time to fall from X to Z will be 6.5 +2 = 8.5 s