During August, 2015, Baxter's Supply Store generated revenues of $60,000. The company's expenses were as follows: cost of goods sold of $36,000 and operating expenses of $4,000. The company also had rent revenue of $1,000 and a gain on the sale of a delivery truck of $2,000. Baxter's operating income for the month of August, 2015 is a) $23,000. b) $24,000. Oc) $20,000. d) $21,000