A and B set up a joint venture company. Without B's knowledge, A and C agreed to transfer 10% of the shares to C. How did C and A reach an agreement?

First of all, we should make clear the contents of the articles of association and see how much voice A has in the company. After all, it only accounts for 25% of the shares, and the remaining 75% of the shares are owned by others. In this respect, A's right to speak is not great, and it will not reach 50% in any case. So it is still a question whether you can get the transparency and right A you want. You should check more before you make a decision.