A gardening company sells clay flower pots and plastic flower pots. There must be at least 2 pots in each shipment, but there cannot be more than 8 in a shipment. Additionally, the shipment must weigh less than 100 lbs. Each shipment container weighs 20 lbs., and there is 1 lb. of packing material. A clay flower pot weighs 15 lbs., whereas a plastic flower pot weighs 7.5 lbs.