<!DOCTYPE html>
<html>
<body>
<?php
$txt1 = "Изучение PHP";
$txt2 = "W3Schools";
$x = 5;
$y = 4;
echo "<h2>" . $txt1 . "</h2>";
echo "Выучить PHP на " . $txt2 . "<br>";
echo $x + $y;
?>
</body>
</html>