Zonker Inc. purchases 500 units of an item at an invoice cost of $30,000. What is the cost per unit? If the goods are shipped f.o.b. shipping point and the freight bill was $1,500, what is the cost per unit if Zonker Inc. pays the freight charges? If these items were bought on 2/10, n/30 terms and the invoice and the freight bill were paid within the 10-day period, what would be the cost per unit?