A law can be adopted if a majority of the member states vote in favor of it, and the number of states voting in favor of it is more than half of the total number of member.

If you want to know how the Council of the EU will vote on a specific proposal, you can use the voting calculator app. It is a free app that lets you check the final result of a vote. It is easy to use, and you only need to enter the number of states and the voting rule to know if an act can be adopted.