Subtotaling

Please see the attachment...

In the subtotal column, I want to be able to have the total of all the property number associated to a single loan number. If the loan number only has one property record, the subtotal (column E) would equal the total (column D) If the loan number has more then one record... (example: Loan number 33333333) then the subtotal would be the same for all three property numbers, and this would be a sub of all three totals (D4+D5+D6)

Thanks!