heatskillz

hi guys, i was wondering on how the ATAR is calculated.. basically im sitting for my hsc next year, is ATAR calculated by my rank in school say im coming 2 in 2u maths with a mark of 80 for my assessments all together and in the hsc i get a 50 does my mark get pulled to 80 ? (is it based on my rank).. and is it possible that i get in the 80s for my ATAR im doing well so far in all subjects i came 1st 2nd and 4th, my subjects are

english standard
2u maths
physics
modern history
visual arts
Thank you!