<select>
    <option value="0">Select</option>
    <option value="-5">Answer 1</option>
    <option value="5">Answer 2</option>
</select>

<select>
    <option value="0">Select</option>
    <option value="-5">Answer 1</option>
    <option value="5">Answer 2</option>
</select>

var score = 0;
var scoreNew = 0;
$('select').change(function() {
    scoreNew = parseInt($(this).val()) + parseInt(score);
    $('.total').text(scoreNew);
})

var score = 0;
var scoreNew = 0;
$('select').change(function() {
    scoreNew += Number($(this).val());
    $('.total').text(scoreNew);
})