I also preparing for the professional exam, but i am struggling with migration and COST questions? How i do improve on those ? Any thoughts or suggestions on this ?
You might review the whitepapers, specifically those on the Cost pillar of the Well-Architected Framework.
For Migrations, there are quite a few. Go to the AWS Whitepaper site and just search on Migration. You’ll notice that there’s lots of overlap among whitepapers so when you start seeing duplicate concepts over and over, you can feel more confident that you’ve covered what will likely appear on the exam.