could use some help understanding!!

Bistrol Corporation uses the weighted average method in its process costing system. This month, the beginning inventory in the first processing department consisted of 800 units. The costs and percentage completion of these units in beginning inventory were: Materials costs Conversion costs Cost $ 15,700 $ 7,700 Percent Complete 75% 20% A total of 8.400 units were started and 7.500 units were transferred to the second processing department during the month. The following costs were incurred in the first processing department during the month: Materials costs Conversion costs Cost $ 186,300 $ 329,800 The ending inventory was 70% complete with respect to materials and 60% complete with respect to conversion costs The cost per equivalent unit for conversion costs for the first department for the month is closest to O $41.59 $38.71 $39.61 $36.68