The Morgan Company uses the weighted-average method in its process costing system. For a particular department, the company had 54,000 equivalent units with respect to conversion costs in March. There were 7,500 units in the department's beginning work in process inventory, two thirds complete with respect to conversion costs. During March, 52,500 units were started and 50,000 were completed and transferred out of the department. The ending work in process inventory in the department: A. consisted of 5,000 units. B. consisted of 2,500 units. C. was 65% complete with respect to conversion costs. D. was 40% complete with respect to conversion costs.

The answer is D. I studied weighted-average method from book, and understood concept, but somehow I can't figure this out. Please elaborate for me if you are an expert on this. Thank you.