Sabavno
Here's the SQL, you just need to change the table name (assuming you have a Yes/No field type rather than text that says 'yes' or 'no')...
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SELECT Transit, Sum(IIf([USRoaming]=True,120,100)) AS Charges
FROM tblExample
GROUP BY Transit;
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I'll just add that you might find it easier to modify your tables, so that instead of a 'US Roaming' field in the first table, you have a 'ChargeFrID'. You then have a Charges table that would have fields: ChargeID, Charge Amount, Charge Description. If it's a relational database, you can link the tables together on ChargeID(One) = ChargeFrID(Many). If it's not a relational database, you still have a valid link for query building.
AutumnBlues