My cart give a wrong total after severalupdates

My cart give a wrong total after severalupdates

1. 6.if($_SESSION['cart'][$f]['id']==$id){
$_SESSION['cart'][$f]['qty']=$qty; $f=$k;}//GET QTY 7. $f++;}
8.$query="SELECT price FROM computer_shop.product WHERE pid='$id'";
//QUERIES TO RETRIVE //PRICE FEOM DB 9.$run=mysql_query($query) or die
('Query error'); 10.$result=mysql_fetch_array($run);
$price=$result['price']; // PRICE OBTAINED 11.//FORMULA TO UPDATE CART 12.
//$sumUp=$_SESSION['cart'][$k]['qty']*$price; 13.
//$_SESSION['total']=$_SESSION['total']+$sumUp-$price; 14.
$_SESSION['total']=$_SESSION['total']+($_SESSION['cart'][$k]['qty']+1)*$price;
25.header('location: viewCart.php'); } ?>