How to write a formula that uses Numerical constant linked to filter selection (drop down)?

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1

This would be the logic:

e.g.:

Case

when CONTAINS_TEXT(Country drop down,“us”) then ((Clicks0.0152000)-Cost)

when CONTAINS_TEXT(Country drop down,“uk”) then ((Clicks0.0181500)-Cost)

ELSE ((Clicks0.0121000)-Cost)

END

So far I have been getting an error that dimensions can not be combined with metrics in formulas.

Thanks a million for your help.