Purrfect Pets uses the perpetual inventory system. At the beginning of the quarter, Purrfect Pets has $32,000 in inventory. During the quarter the company purchases $8,200 of new inventory from a vendor, returned $900 of inventory to the vendor, and took advantage of discounts from the vendor of $220. At the end of the quarter the balance in inventory is $27,500. What is the cost of goods sold?

a $11,580

b $12,700

c $13,200

d $4,500