You said that you put your script in /var/www/html
So the link might be
localhost/html/test.php
Also check the error log file for PHP error.
# cat /var/log/apache2/error.log
EDIT: Change your quote, ” are for Word document and not programming ;-)
<html>
<head>
<title>PHP Test</title>
</head>
<body>
<p>This is an HTML line</p>
<?php
echo "This is a PHP line";
phpinfo();
?>
</body>
</html>