You accidently throw your car keys horizontally at 8.0 m/s form a cliff 64m high. how far from the base of the cliff should you look for the keys?

The formula that applies to the problem is this equation on projectile motion expressed as:
y = x tan θ − ½ g x2 / (v0 cos θ)^2.
We are given with y equal to 64 m , θ is zero degrees and vO equal to 8.0 m/s. By substitution, the x then is equal to 28.91 meters.