present value of "past" and future amounts

[Tim]

Hi, I am trying to compare two financial scenarios.
In both of them I have:
- years when the money is earned or will be earned (lets say A2 – A10)
- Amounts of money earned in the past and those which will be earned (lets
say B2 – B10)

Which formula do I use to calculate the NetPresentValue of all the money
(past and future)?

Thanks, thanks, thanks........