You're trying to add objects, not the value of the objects.
var adult = document.getElementById('adult').value;
Also, + in JS means "concatenate" unless you indicate that it needs to be math.
parseFloat(adult + child + senior... );
If anyone knows of a website that can offer ColdFusion help that isn't controlled by neurotic, pedantic jerks* (stackoverflow.com), please PM me with a link.
* The neurotic, pedantic jerks are not the owners; just the people who are in control of the "popularity contest".