Mr. Beautiful, an organization that sells weight training sets, has an ordering cost of $40 for the BB-1 set (BB-1 stands for Body Beautiful Number 1). The carrying cost for BB-1 is \$15 per set per year. To meet demand, Mr. Beautiful orders large quantities of BB-1 4 times a year. The stockout cost for BB-1 is estimated to be $10 per set. Over the past several years, Mr. Beautiful has observed the following demand during the lead time for BB-1: The reorder point for BB-1 is 50 sets. What level of safety stock should be maintained for BB-1? The optimal quantity of safety stock which minimizes expected total cost is sets (enter your response as a whole number)