A family of Microsoft word processing software products for creating web, email, and print documents.
Word field codes cannot perform calculations based on checkbox values. Rather than using checkboxes, you might consider using dropdown formfields with Yes/No answers and their 'calculate on exit' property set in a document will 'filling in forms' protection applied. You could then do the calculation with a formula field coded like:
{={IF{REF Dropdown1}= "Yes" 5 0}+{IF{REF Dropdown1}= "Yes" 15 0} # 0}
Note: The field brace pairs (i.e. '{ }') for the above example are all created in the document itself, via Ctrl-F9 (Cmd-F9 on a Mac); you can't simply type them or copy & paste them from this message. Nor is it practical to add them via any of the standard Word dialogues. The spaces represented in the field constructions are all required.