Fill form fields from dbase

Tricky question and I don’t even know if it is possible.
A dbase table contains field names: “numberofpersons” having values like “4 persons, € 114,00 per night”. Another field named “totalpersons” gives, in this case, the number 4.
I have a form that contains a select for the number of persons that will occupy a home. The dropdown will show something like “4 persons, € 114,00 per night”. The value for that specific field will contain the price “114,00” for calculation purposes.
Below that I have an input field (that will be hidden later). I want that to show the equivalent of “totalpersons” as selected in “number of persons”. I hope this makes any sense