I suggest to watch following videos -What is EVM in Project Time Management
https://www.youtube.com/watch?v=MO6EOMd-CkA
https://www.youtube.com/watch?v=pC1-TwwKkq8
https://www.youtube.com/watch?v=50J0Whi_hjY
You can watch these videos, the exam will not ask questions for the calculations. You just need a high level idea.