I don’t think this is possible with formulas at all. Instead I would suggest restructuring your data so that you would have an array of objects with the stateRates like
If you just want to map your item.state to have “-ca” (or whatever the selected page variable is) after it in new stateRate property, you can use MAP(data.state, {“id”: item.id, “stateRate”: item.state + "-" + pageVars.state)}) to change property name and add some more chars to the property value.