Rozman Company produces calendars in a one department process. The following data is available for the past month:

Work in process inventory, Beginning 0

Units Started 15,000

Units completed and transferred 12,000

work in process inventory, ending 3,000

direct materals added $30,000

direct labor $20,700

factory overhead costs $10,350

The units in process at the end of the month are 100 percent complete with repects to direct materials and 50 percent complete with respect to conversion costs. What are the equivalent units for conversion costs for the month?

a. 15,000

b. 13,500

c. 3,000

d. 12,000