Updating DIVs When Value Changed From Combo Boxes

I will show u my code pages.
addcart.php
<?php
require_once("../Connection/connection.php");
if(!$_POST['img']) die("There is no such product!");
$img=mysql_real_escape_string(end(explode('/',$_POST['img'])));
$q_result=mysql_query("SELECT * FROM tbl_items WHERE item_photo='".$img."'");
$row=mysql_fetch_assoc($q_result);
$period = $_POST['period'];
$count = $_POST['count']; .....

$('a.button').css('display','block');
$('#cart-text').css('display','none');
}else// hide them{
$('#total').html('');
$('a.button').hide();
$('#cart-text').css('display','block');
}}

My problem is I want to update the totalprice div, when I change the value from the combo boxes. I just want to calculate the rate and the quantity and update it to the totalprice div. But now it is not working. I am retrieving the rate from a database using another php file shown in that script.js. All the values are retrieving and working fine. I use ajax drag and drop care script there. [URL]