Proportional division of a number

Trying to work out how I can create a range or slider configuration where I can specify a dynamic series of divisions of a number. Imagine a pie chart where the pie stays full but then you modify the size of pieces and the other pieces adjust. I am using this so that I can work out how a certain number of square metres (arising from a site coverage) is allocated as a setback from front, back, left and right side of a block. For example, where 20% is at the front, 60% at back and 10% on each side. I can do this manually but not force it to add up to 100% always.

Hope this makes sense! Thanks for your help!

I hope this is what you want.
The upper one gives the absolute values (the pie pieces) and the lower one gives you the additive values (the knife cuts) (8.0 KB)

That looks like it is EXACTLY what I want, thanks Aris!
Can you tell me what the two components to the right of MERGE is?

the ‘graveyard’ component Mass addition does just what it says,it gives you the incremental and final sum of a list of numbers
the remap numbers remaps a list of numbers from a source domain (s) to another domain (T)
in this case, it remaps the numbers from the domain 0-sum to the domain 0-100