Please explain the solution to this General accounting problem with accurate principles.

Accounting records indicate the following inventory balances for the year 20yy. Calculate the indirect factory costs incurred (manufacturing overhead) for 20yy using the information below: Materials Inventory $30,000/$15,000 Work in Process ievemtoryiso | $20,000 Finished Goods Inventory |$12,000/$22,000 Other Data (for the year 1/1/yy to 12/31/yy): ii 2. Prime costs were $450,000 Twelve times the amount of beginning materials inventory was purchased during the year . Direct labor costs, which make up 35% of conversion costs, were $280,000 . The company maintains an average gross margin of 25%