Thanks for your input. I agree with this.
One thing that's not obvious is how to weigh work in the past vs work in the future (I would weigh that equally)
Another thing is how to weigh the amount of risk taken. B "gave up" his studies and a personal project he had, and B and myself (A) both work for a long time with the doubt that we could make the project successful.
I think A and B should be rewarded somewhat for this, the question is how much.