hohow do you add two numbers using PHP?

[mikewooten]

I would like Shipping costs to be added to the total cost of products and
displayed on the Shopping cart page.
I think in some or most e-commerce sites, they have a option to "enter zip code to calculate shipping costs", how would you do that with PHP?
also does anyone know how to have a shipping cost option and add the shipping costs to the total amount?
here's my site if you want to take a look at it:
http://www.wootenmedia.com/wootenmusic8/
thanks

[TheDefender]

PHP has a section in the Manual right here that has examples of the math operators available in PHP. If you have some code already, we can help you tweak it to your needs... Just post it.