You could first define an xml layout for example
on your php server you have a page called mypage.php
$x = ... you assign a value to x ..;
echo "<result><x>" .$x."</x></result>";
your android app makes a call to http://domain-name/mypage.php
and gets as result "<result><x>5</x></result>"
parse the result and you have the value of x in your app
or if your php page is generating HTML (ie a page which is normally displayed via a browser) you can do the same but then you'll have the parse the HTML and search for the specific values you're looking for