Using the perpetual inventory system, journalize the entries for the following selected transactions:

A. Sold merchandise on account, for $12,000. The cost of the merchandise sold was $6,500.

B. Sold merchandise to customers who used MasterCard and VISA, $9,500. The cost of the merchandise sold was $5,300.

C. Sold merchandise to customers who used American Express, $2,900. The cost of the merchandise sold was $1,700.