[Plugin: price-calc] Formula help

This plugin does exactly what I need, but I am having some trouble working out what to put in the ‘formula’ box.

I am quoting on producing books, what I want to say in normal maths is:
(size * pages + binding * quantity) + (pagedesign * pages) = total

However, because I can’t use brackets the string ends up as:
+size
*pages
+binding
*quantity
=paper
+pagedesign
*pages

The problem being that it ends up multiplying the whole amount by ‘pages’ rather than just multiplying ‘pagedesign’ and adding it to my subtotal

https://www.ads-software.com/extend/plugins/price-calc/