Thanks a lot for you help!

I'm building a financial app and I need some help with making a "distribution coefficient/index" (best math name I could give it ). The idea behind it is:

- There's a total balance. Let's call it "X".

- There are users with different shares at stake on "X": A, B, C and D (users).

- Each user has a % allocation depending on how much they have at stake on "X". Let's say:

- A --> 10 units --> 10%

- B --> 20 units --> 20%

- C --> 30 units --> 30%

- D --> 40 units --> 40%

X = 100 ---> 100%

I need a coefficient (let's call it "Y") capable of determining the new allocation % of each user once any of them has added more units to "X", and the formula to calculate this coefficient. It would be something like:

oldUnits + newUnits

- A --> 30 (10 + 20) --> Y --> 25%

- B --> 20 --> Y --> 16.66%

- C --> 30 --> Y --> 25%

- D --> 40 --> Y --> 33.33%

The limitations/constraints/requirements/etc. are:

- The only parameter that I (my app) can freely modify is "Y".

- The users are in charge of modifying their own stake of "units".

- The % allocation is the result of the interaction of "units" with "Y" and it must return 100% when adding up the % allocation of all users.

I don't have any high-level math background (mine it's business), so go easy on me please.

Thanks a lot again for your help!

Cheers.