PHP - Using AND in if else properly

How to use AND in if else statement in PHP properly?

This is my code.

<?php if ($namamapel['tampil_pg'] != 0) { ?>
     <?= $namamapel['tampil_pg'] ?><p> Multiple Choice</p>
<?php } elseif ($namamapel['tampil_esai'] != 0) { ?> 
     <?= $namamapel['tampil_esai'] ?><p> Essay</p>
<?php } elseif ($namamapel['tampil_pg'] != 0) && ($namamapel['tampil_esai'] != 0) { ?>
     <?= $namamapel['tampil_pg'] ?><p> Multiple Choise, </p> <?= $namamapel['tampil_esai'] ?><p>Essay
<?php } ?>

When I run the code, I get mydomain.com is currently unable to handle this request | HTTP ERROR 500.

Any help please? Thank you in advance.