@Chapa; sanırım böyle bi' şey istiyordunuz?
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
</head>
<body>
<form method="POST">
<label for="ali">Ali</label>
<select id="ali" name="ali">
<?php foreach(range(5, 1000) as $val): if($val % 5 == 0): printf('<option value="%s">%s</option>', $val, $val); endif; endforeach; ?>
</select>
<label for="veli">Veli</label>
<select id="veli" name="veli">
<?php foreach(range(5, 1000) as $val): if($val % 5 == 0): printf('<option value="%s">%s</option>', $val, $val); endif; endforeach; ?>
</select>
<button type="submit">Hesapla</button>
<?php
if(isset($_POST["ali"]) && isset($_POST["veli"]))
{
if($_POST["ali"] > $_POST["veli"])
{
$fark = $_POST["ali"] - $_POST["veli"];
printf("Veli Ali'ye %s TL borçlu", $fark);
}
else if($_POST["ali"] == $_POST["veli"])
{
echo "Ne Ali'ninde Veli'ninde birbirine borcu yok";
}
else
{
$fark = $_POST["veli"] - $_POST["ali"];
printf("Ali Veli'ye %s TL borçlu", $fark);
}
}
?>
</form>
</body>
</html>