bill.php

  <?php
$bill = 0;
$tip = 0;
$num_people = 1;

  if(isset($_POST['num_people']))
      $num_people = $_POST['num_people'];
    if(isset($_POST['tip']))
      $tip = $_POST['tip'];
    if(isset($_POST['bill']))
        $bill = $_POST['bill'];

  echo "billy: ".$bill . "<br>";
  echo "tip: " .$tip. "<br>";
  echo "numpeople: " . $num_people. "<br>";
  $tip=$_POST['tip'];
     $bill=$_POST['bill'];
     $num_people=$_POST['num_people'];
         $total = ($bill * $tip) * $num_people;
         echo "Each person owes $total";


?>
  <html>
<body>
<div id="wrapper">

<h3>Bill Calculator</h3>

<form action="bill.php" method="post">

<p>Number of people eating:
<select name="num_people">
        <option value="1">1</option>
        <option value="2">2</option>
        <option value="3">3</option>
        <option value="4">4</option>
        <option value="5">5</option>
        <option value="6">6</option>
        <option value="7">7</option>
        <option value="8">8</option>
</select>
</p>

<p>Amount of meal bill: <input type="text" name="bill"></p>

<p>Tip percentage:
<select name="tip">
        <option value=".15">15%</option>
        <option value=".18">18%</option>
        <option value=".20">20%</option>
</select>
</p>

<p><input type="submit" value="Calculate"></p>

</form>

</div>

</body>
</html>