There is nothing we can do about that. It's your board decision. State examination board decides the rules. It's okay you didn't have 75% marks you still can get admission to Universities and colleges. Many of the colleges including central universities the eligibility criteria for applying entrance exam is 50% about or for OBC it is 40% above. Majority of entrance exam have their eligibility criteria as candidate should be passed 12th from a recognised board with a mark percentage 45% or 50%. It depends and various according to the entrance exams. You don't have to worry about that. Also there are many colleges that give admission.

Thanks