Topic awaiting preservation: Project Management

Ok I am working on a project manager to keep track of work time, cost, and all that jazz. Right now I have things set so that I can manually enter percentages of project and sub-project completion (and even sub-sub-projects...etc.). Not being even close to a mathematician, I was wondering what the basis for coding a script that does the folllowing would be: (I am using PHP and MySQL)

1. Setting a sub-project's weight (and storing to db) so that when I update the percentage completed, it will return a value to the root project and sum it against all other sub-projects according to weight. Here is a visual example:

Main Project (var TOTAL) ===>figure X

<B>

Am I looking at doing something like this?:

.% complete of sub-project * %weight of sub-project = root's % completed?

Nevamind, I figured it out...