Aiming for the Bull's Eye: Accounting for Gravity

[VashtheStampede]

an acher shatneds 40m away from his target. If the arrow is shot horizontally with a velocity of 90m/s how far above the bull's eye must he aim to compensate for gravity pulling down. No air resistance and I guess the target is level with him.

 

[berkeman]

How long does it take for the arrow to reach the target? How far would the arrow fall vertically in that amount of time?