Cumulative Percentage Allocation Question on Excel 2010

Hello, Im new to this forum because I need some big help on this project im working on.

I have several projects going on and within those projects there are separate Sub-Projects that need to get done before the entire project to be complete.

I know that I can use the sum function to add up the percentages in order to get "100%" in the Project completion.

What Im trying to accomplish is setting the sub-projects as I finish them at 100% thus automatically inputting about a 12% completion on the total project.

Only thing is one sub-project can account for 60% of the whole project while others may be like 15% and the other being the remaining 25%

In the example below the Adwords Campaign: there are 3 sub projects: Marketo Landing Page (60%), UTM Coding is (15%), and Segmenting is the remaining (25%)

Since "marketo landing page", and "utm coding" have been completed they are at 100% for the subproject. Culminating to 75% of the entire project, with the 25% remaining at 0% as we have not started.

I manually input those numbers to give you an idea of what I want it to look like, but need help on the formular to use in order to make this work correctly. Thank you for your time in reading this long and probably a bit confusing post.

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