At the county 4th of July fair, a local strong man

Last updated: 8/6/2022

At the county 4th of July fair, a local strong man challenges contestants two at a time to a tug-of-war contest. Contestant A can tug with a force of 390 pounds. Contestant B can tug with a force of 320 pounds. The angle between the ropes of the two contestants is 30°. With how much force must the local strong man tug so that the rope does not move?