Update Selected Checkbox

<form method="post" action="" autocomplete="off">
<input type="submit" name="update">
<table width="100%">
<tr>
    <td valign="center"><input type="checkbox" name="up[]" value="51"></td>
    <td>51</td>
    <td>ex</td>
    <td>ex</td>
    <td>Sparepart</td>
    <td>1</td>
    <td><input type="text" name="qty[]"></td>
</tr>
<tr>
    <td valign="center"><input type="checkbox" name="up[]" value="52"></td>
    <td>52</td>
    <td>ex</td>
    <td>ex</td>
    <td>Sparepart</td>
    <td>1</td>
    <td><input type="text" name="qty[]"></td>
</tr>
<tr>
    <td valign="center"><input type="checkbox" name="up[]" value="53"></td>
    <td>53</td>
    <td>ex</td>
    <td>ex</td>
    <td>Sparepart</td>
    <td>1</td>
    <td><input type="text" name="qty[]"></td>
</tr>
<tr>
    <td valign="center"><input type="checkbox" name="up[]" value="54"></td>
    <td>54</td>
    <td>ex</td>
    <td>ex</td>
    <td>Sparepart</td>
    <td>1</td>
    <td><input type="text" name="qty[]"></td>
</tr>
</table>
</form>

<?php
if (isset($_POST['update'])) {
  $jumlah = count($_POST['up']);
    for ($i=0; $i < $jumlah; $i++) {
      if (!empty($_POST['up'][$i])) {
      echo $_POST['up'][$i].' - ';
      echo $_POST['qty'][$i].'<br>';
      }
    }
}
?>