PHP - Calculadora pagina web

<?php

//error_reporting(E_ALL);

//ini_set('display_errors', '1');

require("configOR.php");

if(isset($_POST["btn_calcular"])) {  //si hem seleccionat el boto "calcular"

      ## PASSEM VARIABLES

      $txt_grams = $_POST["txt_grams"];

      $txt_preu9 = $_POST["txt_preu9"];

      $txt_preu12 = $_POST["txt_preu12"];

      $txt_preu14 = $_POST["txt_preu14"];

      $txt_preu18 = $_POST["txt_preu18"];

      $txt_preu22 = $_POST["txt_preu22"];

      $txt_preu24 = $_POST["txt_preu24"];

      $txt_data = $_POST["txt_data"];

      $txt_noticia = $_POST["txt_noticia"];

      ## CALCULEM IMPORTS

      $txt_import9 = round($txt_preu9 * $txt_grams,2)." €";

      $txt_import12 = round($txt_preu12 * $txt_grams,2)." €";

      $txt_import14 = round($txt_preu14 * $txt_grams,2)." €";

      $txt_import18 = round($txt_preu18 * $txt_grams,2)." €";

      $txt_import22 = round($txt_preu22 * $txt_grams,2)." €";

      $txt_import24 = round($txt_preu24 * $txt_grams,2)." €";

} else {                              //es la primera vegada que obrim la plana

      ## CONECTEM BASE DE DADES

      $conexio = @mysql_connect($db_ser,$db_usu,$db_pas);

      @mysql_select_db($db_nom,$conexio);

      if ($conexio == FALSE){

          echo ('Error en la conexion !!!');

          exit();

      }

      ## LLEGIM ELS PREUS DE L'OR PER GRAM, SEGONS QUILATS

      $result=@mysql_query("SELECT * FROM tblPreus WHERE idPreu = '1' ", $conexio);

      $camp=@mysql_fetch_array($result);

      $txt_preu9= $camp["preu9"];

      $txt_preu12= $camp["preu12"];

      $txt_preu14= $camp["preu14"];

      $txt_preu18= $camp["preu18"];

      $txt_preu22= $camp["preu22"];

      $txt_preu24= $camp["preu24"];

      ## INICIALITZEM VARIABLES DE CALCUL

      $txt_grams="";

      $txt_import9=" ";

      $txt_import12=" ";

      $txt_import14=" ";

      $txt_import18=" ";

      $txt_import22=" ";

      $txt_import24=" ";

      ## LLEGIM LES NOTICIES

      $result=@mysql_query("SELECT * FROM tblNoticies ORDER BY Data DESC", $conexio);

      $camp=@mysql_fetch_array($result);

      $txt_noticia = $camp["castella"];  //noticia en castella

      //$txt_noticia = $camp["catala"];  //noticia en catala

      $txt_noticia = str_replace("'","´",$txt_noticia);

      $txt_data = substr($camp["data"],8,2)."/".substr($camp["data"],5,2)."/".substr($camp["data"],0,4);

      ## TANQUEM BASE DE DADES

      mysql_free_result($result);

      mysql_close($conexio);}

?>