$(function() {
    $('input[path="add"]:checkbox').change(function() {
        var total = 0;
        $('input[path="add"]:checked').each(function() {
            total += parseInt($(this).val());
        });
        total += parseInt($('#more').val());
        $('#usertotal').html(total);
    });
    $('#more').change(function() {
        var selectVal = $(this).val().trim();
        if (parseInt(selectVal) > 0) {
            $("#span").html("<b>more addons:</b> " + selectVal);
        } else {
            $("#span").html("");
        }
        $('input[name="ch1"]:checkbox').trigger('change');
    });
});

Setting Validate Copy Format

<div id="container">
  <h1>
    Add-ons
  </h1>
  <input type="checkbox" name="ch2" value="10" id="qr1" path="add"/>
  Add-on Number 1 - 10 QR 
  <br />
  <input type="checkbox" name="ch1" value="20" id="qr1" />
  Add-on Number 2 - 20 QR 
  <br />
  <input type="checkbox" name="ch1" value="40" id="qr1" />
  Add-on Number 3 - 40 QR 
  <br />
  <input type="checkbox" name="ch1" value="60" id="qr1" />
  Add-on Number 4 - 60 QR 
  <br />
</div>
<div>
  I want more add-ons
  <select id="more" name="more">
    <option value="0 QR">
      0
    </option>
    <option value="30 QR">
      1
    </option>
    <option value="50 QR">
      2
    </option>
    <option value="100 QR">
      3
    </option>
  </select>
  <span id="span">
  </span>
  User total usage: 
  <span id="usertotal">
    
  </span>
</div>

Copy Format

Download