Hey all,

Ive been going a little crazy past two days because i cant figure out a
function to get the value of a previous member...
Heres my problem: I have two tables that each contain values i need. In
Table1 there is a totalCost column, in Table2 there is a cumulative
profits column.
Now the calculation i need should show a new column in Table1 called
'AddedValue' and the calculation should look like this:

AddedValue=(CurrentTotalCost-PreviousTotalCost)-(CurrentCumulativeProfits-PreviousCumulativeProfits)

Any help is appreciated as i know this is a simple calculation, but
driving me insane none the less.

Cheers,