PHP syntax not working in localhost -

I was trying to execute this piece of code

I am using XAMPP server as editor and notepad ++. I saved the file as the firstfile2.php in the htdocs folder which is stored in the D drive. When I am running this file, I get this code as output and not 10. Is anyone wrong?

1. In the browser you need to navigate

2. Ensure that your file is not actually called firstfile2.php.txt Because you did not save it properly

3. Make sure you have the full php tag (some open tags some servers Is not enabled by default)