automation - After Effects expressions to sum numbers and control charts

I would like to build a project in which I will change two numbers and all of the following take place automatically! I'll Explain...

Part 1:

I have two layers, "Number 1" and "Number 2". Suppose I give "Number 1" the value 15 and "Number 2" the value 5. Automatically I want a new layer to sum these numbers (20).

Part 2:

Next, I would like to built a chart below to update automatically according to the numbers that I gave.

From the above sum, I want the layer with the value 20 to automatically correspond to 100% in the chart. So the chart shapes change automatically and understand that "Number 1" with the value 15 is 75% (15*100/20) and "Number 2" with the value 5 is 25% (5*100/20).

Probably I need for the value of the numbers a Solid with a Numbers effect and not a text? And if someone knows the expressions...