Question

a bullet is fired horizontally with a velocity of 40 m/s from a height if 50m. how far it will fall to the ground

Answer 1

50m, of course.

you want to rephrase the question?

also, recall that the height h is
h = 50 - 4.9t^2

use that t in figuring
distance = speed * time

Answer 2

15.8m