Materials costs of $300,000 and conversion costs of $321,300 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 are 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 those units that were completed and transferred out of the process in September?

$276,000

$621,300

$637,800

$586,500

answer and how to do the problem please.