Gbirk co. uses a job-order cost system. the following debits (credit) appeared in birk’s work-in-process account for the month just ended: date description amount 1 balance $ 4,000 31 direct materials 24,000 31 direct labor 16,000 31 factory overhead 12,800 31 to finished goods (48,000) birk applies overhead to production at a predetermined rate of 80% of direct labor cost. job no. 5, the only job still in process at month end, has been charged with direct labor of $2,000. what was the amount of direct materials charged to job no. 5?