Hi,
First of all, please calm down. It isn't the end of the world!
Unfortunately, If you have been getting 20-30% for your sacs in Unit 3, and also ranked last in the cohort, it is most unlikely that you will recover from this. The only way for you to achieve 80+ atar is to allocate most of your time on to your study.
But as others have said, Sacs arent the only factor that determines your study score. It is ultimately the final exam that you must ace in order to achieve a reasonably good study score for your subjects. It is very rare for someone that has been last in the cohort, and somehow get 100% in the exams, but getting an average-high mark would be possible if you were to put in most of your time into study.
Also, I have friends that received bad atar scores but were able to get into uni via diploma. (1 year of diploma and achieving a decent mark to get into 2nd year in the following year. So he isnt behind compared to other uni students.)
When you say difficult, do you mean difficult to get between 30-40 study scores due to my sac scores or difficult because of the minimal effort im most likely putting into vce?
They both can be difficult. Most students fail to achieve 40 study score. But i think you still have chance to achieve 30 if you do 'ace' the exam! If you really want 80 atar, you must put maximum effort from now on. (80+ ATAR is essentially you getting a better score than 80%+ of the state)