<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<?php
for($y=20;$y>1;$y=$y-2z){
$kwadraat=$y*$y;
echo"Het kwadraat van $y is $kwadraat,</br>";
}
?>
</body>
</html>