How to make drop down boxes calculate?

Hi.

For a yes-no question it's easier to use radio buttons, or checkboxes, since it's easier to manage their sum, etc.

You can assign the option for each drop down list for a blank choice, a "Yes" choice, and a "No" choice. . You will then need to write a custom script to count the "Yes" answers and report the count in one field  and then a script in another field to count "No" answers. There should be plenty of examples for this issue already answered, please use the search function to find them.