php提交表单后出现http500异常

php提交表单后出现http500错误

新手，刚接触php，麻烦各位大神了
html部分










php程序





$unpop=$_post["unpop"];
$caramel=$_post["caramel"];
$caramelnut=$_post["caramelnut"];
$toffeynut=$_post["toffeynut"];
$name=$_post["name"];
$street=$_post["street"];
$city=$_post["city"];
$payment=$_post["payment"];
if($unpop=="") $unpop=0;
if($caramel=="") $caramel=0;
if($caramelnut=="") $caramelnut=0;
if($toffeynut=="") $toffeynut=0;
$unpop_cost=3.0*$unpop;
$caramel_cost=3.5*$caramel;
$caramelnut_cost=4.5*$caramelnut;
$toffeynut_cost=5.0*$toffeynut;
$total_price=$unpop_cost+$caramel_cost+$caramelnut_cost+$toffeynut_cost;
$total_items=$unpop+$caramel+$caramelnut+$toffeynut;
?>

Customer:

print("$name
$street
$city
");
?>

Order Information

Product	Unit Price	Quantity Ordered	Item Cost
Unpopped Popcorn	$3:00
Caramel Popcorn	$3:50
Caramel Nut Popcorn	$4:50
Toffey Nut Popcorn	$5:00