AMB (w/o every date listed)

[twofordiving]

Hello!

I am at a loss in trying to figure out the formula for this issue. I am trying to calculate the AMB for a Line of Credit account for my business. The problem is not every date from each month is listed within the table. Only dates when the principal balance changes (from payments or withdrawals). I've attached the excel spreadsheet and was wondering if anyone can help me with this formula?

I need the dates from column A and the Principal balance from column J. The average monthly calculation needs to be put under Column O. They are all highlighted in gold.


Please let me know if you need me to clarify anything else. You will be saving my life if you figure this out. Thank you!!!!