If $2700 of salaries was paid in January, what was the balance in Salaries Payable at December 31, 2009?

Adjusted Trial Balance
January 31, 2010

Cr. Salaries Payable $800
Dr. Salaries Expense 1800.

I think all I have to do is subtract the salaries expense from the salaries paid since the amount that was in salaries payable would have been expensed already in December and was just paid for in January. Am I correct in my thinking of this.

All help is extremely appreciated thank you in advance.

If the actual January salaries expense was 1,800 and yet the company paid out a total of 2,700 during the month, then the month-end payables balance must have decreased by 900 from Dec 31 to Jan 31. (The 2,700 payment covered the 1,800 January expense, plus contributed 900 toward reducing the liability.)

So if the payables ended up on Jan 31 at 800, and that amount represents a 900 reduction from its Dec 31 balance, then at Dec 31 it must've stood at...