How difficult is it to get a 90+ average in Grade 12?

Study, study, study. I cannot say how much Senior year, first semester is important. (As well as 2nd semester junior year.) I am currently a senior in high school as well and am taking all my hard cles this semester. Most schools let you take all of your easy cles second semester since 1st semester matters the most. Also 1st semester is when you want to start sending out all of your college applications (if you have not yet already done so)