Get url parameter in GET request using REST

Hello everyone, I have a question. When I make the request:

  

GET / withdraw / 30

Since the value "30" is not bound to a key, then you can not use $_GET['chave'] .

The way I found it was to do this:

$valor = end(explode("/", $_SERVER['REQUEST_URI']));

It's not very beautiful, but it works.

Is there a better way to do this without using a Framework? In CakePHP I do this well, but without it it complicated the midfield.