Help with PHP code

[Ollie]

I'm in the process of coding an extension and I need to know the code to get the total amount.  I tried these three code snippets, but none of them worked:

<?php echo $totalamout; ?>
<?php echo $total; ?>
<?php echo $total['text']; ?>

I also need the code for the model number of each item on the order.

[ABolm]

What, Where, Why ...

My crystal ball is for maintenance this week.
Last week I had ask a similar question and the high concentration of resulting smoke was very dangerous.

So questions like is $x the right variable, are not productive, nor to answer.
Just my 2 ct.