Short accounting question. Need a little help

Shouldn't take too long

the possible answers are :

20,000

24,000

20,500

19,500

22,500

Berry's boxes manufactures boxes. It expects to sell 20,000 boxes in 2012. the company had enough beginning inventory of direct materials to produce 24,000 units. Beginning inventory of finished units totalled 2,000 with a target ending inventory of 2,500 units. The boxes sell for $3.00 and the company keeps no work-in-process inventory. Direct materials costs for each box total $1.00 while direct labour is $0.50. Factory overhead is $0.20 per box. How many boxes should be produced in 2012