This way the fields are easier to use, and we can get rid of the
placeholders.
Note we're simplifying the `answer_result_value` in order to make it
easier to return `0` instead of `nil` when the field is empty.
Also note there's a small change of behavior here; previously, these
fields were empty by default, and now their value is `0` by default, so
blindly clicking the "Save" button would send `0` instead of an empty
value. I don't think it's a big deal, though, but we need to keep that
in mind.
