Help me to calculate this:a stone is thrown horizontaly from the top of a building 80m height with velocity 12m-1 per second find the time taken to reach the ground

HELP ME PLEASE

The horizontal speed is constant and is irrelevant.

This is simply an 80 meter fall
v = 0 - g t
h = 80 + 0 t - (1/2) g t^2
at ground h = 0
so
g t^2 = 160
if this is around here , g = about 9.81 m/s^2
so
t^2 = 160 / 9.81
t = about 4 seconds