How to adjust collection against agewise outstaning using excel formula

[Petro_2013]

Can Someone tell me how can i adjust monthly collection against age wise outstanding using excel formulas
for example : i have outstanding as below
upto 30 days : 100000
upto 60 days : 20000
upto 90 days : 15000
total Collection : 50000

How will i adjust this collection against the outstanding, i want to clear old outstanding first from collection.

Please reply fast as i need to submit report in 1 day

I have also attached the demo file.



Regards,
Petro_2013