In figure 11-46 two acrobats perform a balancing maneuver. The arms of the top acrobat (in yellow), together with the weight of his head and shoulders, provide a downward force at a distance of 28 cm from the pivot point to balance the torque produced by his lower body. If the lower body of the top acrobat is modeled as a 54-kg mass at a distance of 39 cm from the pivot point, how much force must the arms and upper body produce?