Thanks for query

uppose jee mains percentile = A

And  boards percentile = B

So your merit marks will be

(0.4×A) + (0.6×B) which will be out of 100.

Your ACPC merit rank will be calculated according to your merit marks.

ITNU merit rank is calculated according to JEE mains AIR.

you can find your estimated rank from below link

https://engineering.careers360.com/gujcet-rank-predictor