Why not just prepare for your boards ? Understand your subjects well,develop your reasonings ,understand it’s applications ,take help of your teachers to discuss your understandings by reading the text . Take suggestions for better presentation .
Once you have understood a subject well and know how to present your understandings ,you should know you have done your best .
Let us stop emphasising a culture which gives unnecessary importance to percentages . It creates an unwanted mental pressure which would lower your future performances .
I think it is high time we lower the pressure and understand that there is a reason why people are going into depression and committing suicide because of these percentages.
Boards will pass, but the knowledge would stay . GAIN KNOWLEDGE