Answer 1

Remember, in PHP any variable name is written using a dollar sign ($) so it should have been written $a + $b.

Reading input value is done by referring to the input name in the request, depending on which method used by a HTML form to send its data, you can read from $_POST or $_GET, for example, in HTML form you have two text input with name attribute "firstValue" and "secondValue"; then upon form submit PHP will have those values in:

* Using GET method
$_GET["firstValue"]
$_GET["secondValue"]

* Using POST method
$_POST["firstValue"]
$_POST["secondValue"]

Then you can assign those values into variables so you can do what you want with them.

NOTE: Code Playground doesn't support reading form submission data, you will be better to have a local server for development installed on your machine.

Hth, cmiiw