Staley Co. manufactures computer monitors. The following is a summary of its basic cost and revenue data: Per Unit Percent Sales price $480 100 Variable costs 312 65 Unit contribution margin $168 35 Assume that Staley Co. is currently selling 600 computer monitors per month and monthly fixed costs are $80,000. Staley Co.'s margin of safety ratio (MOS%) if 600 units are sold would be (round intermediate calculation up to nearest whole number of units):