Hello

For CMAT exam (for admission in MBA and PGDM course) you have to have a minimum of 15 years of formal education from a recognized board as well as 50% in your graduation. Since you have 80% you have cleared the requirement and are eligible to apply for the CMAT exam.

That being said, you must clear the backlog before the counselling begins (after the CMAT result is declared). If you have a backlog in graduation during your counselling it means you have not graduated from that institute yet hence try to clear it as soon as possible.

All the best!