sir, i get rt/fail in 3 subject of improvement exam sir kya mera pichla wala mark sheet valid rhega ya phirse paper hoga???
As per the information available, if there is increase in marks then only there will be changes in the marksheet else the old marks will be the valid score for the boards. So your previous marks will be valid if there are no improvements corresponding to the subjects.
Don't worry if you have passed the subject previously then you won't be made fail as you as have failed in the improvement examination.
I hope this answer helps. All the very best for your future endeavors!