Americana Replics is owned and operated by a craftsman who makes replicas of historic firearms for museums, sportsmen, and collectors. He is currently producing 63 flintlock muskets per month. Cost data for the muskets are as follows:

Price per unit $750 Variable costs per unit 480 Fixed costs per month 8,400

If Rustic expects to sell 60 units per month, how much is his margin of safety expressed in sales revenue?