WP Form Process template

<?php get_header();
/*
Template Name: Calculate Page
*/

if(isset($_POST['submit'])){
  $amount = $_POST['amount'];
  $price = $_POST['price'];

  $total = $amount * $price;
}

if (have_posts()) : while (have_posts()) : the_post(); ?>

  <h1>How much will you make</h1>
 	<?php the_content(); ?>

  <?php endwhile; endif; ?>


<div class="col-xs-7">
<form class="form-horizontal" action="" method="POST">

 <div class="form-group">
    <label for="amount" class="col-sm-2 control-label">Amount:</label>
    <div class="col-sm-10">
      <input type="text" class="form-control" name="amount" value="<?php echo (isset($_POST['amount'])) ? $_POST['amount'] : ''; ?>" id="amount" placeholder="">
    </div>
  </div>

   <div class="form-group">
    <label for="price" class="col-sm-2 control-label">Price:</label>
    <div class="col-sm-10">
   <input type="text" class="form-control" name="price" id="price" value="<?php echo (isset($_POST['price'])) ? $_POST['price'] : ''; ?>" placeholder="">
    </div>
  </div>

  <div class="form-group">
    <div class="col-sm-offset-2 col-sm-10">
      <button type="submit" name="submit" class="btn btn-primary">Submit</button>
    </div>
  </div>

<?php 
if(isset($total)){
	echo '<div class="alert alert-success"> You will make '.$total.'</div>';
}
?>
</form>

</div>




<?php get_footer(); ?>