Please help me !!? I am desperate !?

-After finishing high school, if your grades are low, can you do something to get them higher ? Like a virtual school session or something similar ? For example: i have 75% in math. For a certain college, i need 80%. Can i do something or study somewhere to get a better grade, higher than 80% ?



P.S



I still have one year left until college , but i want my secondary 4 grades to raise. So, is there a way to get those grades higher after graduation ? Please answer me.