how did I find out the answer to........

Greatwater Manufacturing uses job costing. In May, material requisitions were $44,000 ($39,000 of these were direct materials), and raw material purchases were $57,700. The end of month balance in raw materials inventory was $24,300. What was the beginning raw materials inventory balance?

A) $10,600

B) $43,000

C) $72,400

D) $25,300