Trying to find beginning inventory for a production budget?

okay, i am having alot of trouble trying to find out what the beginning inventory is for this problem. my beginning balances are: ets: cash $46000, acct reciev. 51000, raw materials 5200, finished goods 39270, land 20000, building 127000, equipment 43500. liabilities: ac. dep. 43000, acct payable 6340, common stock 80000, retained earnings 202630. okay now that i have that information i know that the company wants to have 3000 finished units on hand at the end of each month. and the units are $21.00 per unit. the materials are .2lbs per unit and is selling for $13.00 per pound. the units that are expected to sale are january 5000 units, february 9000 units, and march 7000 units. so, if anyone knows how to atleast find the beginning inventory, i would love to learn how! thanks!