I don't think you could accomplish this with static text, but you could do it if you used a read-only text box and an import formula:
Leave your code values at the end of your drop list selections. Then look at the right x characters. So the final would look something like this...
$RIGHT(Tip de celula,2)$RIGHT(Numar de carucioare,2)$RIGHT(Tip de incalzire,1)-$RIGHT(Tip de generator,3)
(You'll need to pick the variables from the variable list, you cannot add these in exactly as shown.)
I receive a solution from my VAR. It would not be easier if I do this formula with list with aliases?