travel time:

a projectile is fired at a speed of 840 m/sec at an angle of 60 degree. how long will it take to get 21km downrange?

here is what i did an its no where close to right. the answer was 50seconds i got no ideal how to get that. here is what i attempted to do.

http://i176.photobucket.com/albums/w...titled-173.jpg