I have following set of data in my Excel worksheet.

Column A - Todays Sales Value
Column B - Todays Payment

Based on above, followings columns are configured for
Column C - Opening Bal
Column D - Cumulative Purchases
Column E - Cumulative Payments

Now in following columns I desire to get

Column F - Payment for Todays Sale
Column G - Advance Payment Received
Column H - Payment for Old Dues

What best function I can put in each column.
Thanks in advance.

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Alisaheb