How do I use print isset on this from?

[frank_solo]

How do I print isset on this form? Thanks

<?php $var = $result['email'];
if (!empty($var)) {

if (isset($_POST['submit'])) {	

if(isset($_POST['answer']) && $_POST['answer'] == '2'){
$to       = "$var"; // change to your email address
$name     = htmlspecialchars ($_POST['name']);
$email    = htmlspecialchars ($_POST['email']);
$phone    = htmlspecialchars ($_POST['phone']);
$msg      = htmlspecialchars ($_POST['msg']);
$d        = date('l dS \of F Y h:i:s A');
$sub      = "My Domain RE:".$result['title']."";
$headers  = "From: $name <$email>\n";  
$headers .= "Content-Type: text/plain; charset=iso-8859-1\n";
$mes      = "phone: ".$phone."\n";
$mes     .= "Message: ".$msg."\n";
$mes     .= "Name: ".$name."\n";
$mes     .= 'Email: '.$email."\n";
$mes     .= 'Date & Time: '.$d;
mail($to, $sub, $mes, $headers);

echo "<div align='center'<span style='font-family: Tahoma, Geneva, sans-serif; font-size: 14px; color: #F00;'>Email Has Been Sent</span></div>";
} else {

echo "<div align='center'<span style='font-family: Tahoma, Geneva, sans-serif; font-size: 14px; color: #F00;'>ANSWER does not match! </span></div>";

}

} 
echo "<div align='center'><span style='font-family: Tahoma, Geneva, sans-serif; font-size: 14px; color: #00F;'>Email: ".$result['contact']."</span></div>
<form method='post' action='apt.php?id=$id' name='contact' onSubmit='return Blank_TextField_Validator()'>
<input name='name' type='text' size='40' placeholder='Name' value='".preg_replace('/[^a-z\-_0-9\.:\/]/i','',$_POST['name'])."'/><br>
<input name='email' type='text' size='40' placeholder='Email' value='".preg_replace('/[^a-z\-_0-9\.:\/]/i','',$_POST['email'])."'/><br>
<input name='phone' type='text' size='40' placeholder='Phone' value='".preg_replace('/[^a-z\-_0-9\.:\/]/i','',$_POST['phone'])."'/><br>
<textarea name='msg' cols='29' rows='4' value='".preg_replace('/[^a-z\-_0-9\.:\/]/i','',$_POST['msg'])."' id='msg'></textarea><br>
<div align='left'><span style='font-family: Tahoma, Geneva, sans-serif; font-size: 12px; color: #000;'>What is 2 + 2? </span><br><span style='font-family: Tahoma, Geneva, sans-serif; font-size: 12px; color: #000;'>Answer: </span><input name='answer' type='text' id='answer' size='3' maxlength='3' /><input type='submit' class='button4' value='Send' name='submit' /></div>
</form><br><br><br>";}?>