I can't seem to figure this one out. Don't know if the answer isn't there or what. Thanks.

Materials costs of $600,000 and conversion costs of $642,600 were charged to a processing department in the month of September. Materials are added at the beginning of the process, while conversion costs are incurred uniformly throughout the process. There were no units in beginning work in process, 100,000 units were started into production in September, and there were 8,000 units in ending work in process that were 40% complete at the end of September What was the total amount of manufacturing costs assigned to the 8,000 units in the ending work in process? a) $69,600 b) $48,000. ) $40,800. d) $21,600