I don't know which boards you are talking about and the subject/stream you are concerned about. But in general, if you have good understanding and conceptual skills and if you solve the exercises then you will have good possibility to get a good percentage in your boards.

See boards demands you to prepare the syllabus thoroughly so if you study regularly and practice the previous year question papers and moreover if you spent time on concept building then you will easily be able to score above 80% and not only that if you build your concepts well then in your UG course or in any entrances you will be able to score good. So be regular in your studies and choose the resources of studying wisely. Also it would be better if you can give mock exams for boards as it will help you to get a time management skill.

I hope this answer helps. All the very best for your future endeavors!