can u guys possibly tell me in around about percentages...we don't do study scores in perth 
Well, just from light reading (and not having anything better to do on a Friday evening), assuming no LOTE, for a 90 ATAR you need around 70 scaled average, 95 ATAR a 76 average, 99 an 86 and for a 99.5, 90 across your subjects.
I've no idea how scores are scaled, but according to
this: there's certain statistics for each scaled score - like for Chem you need to be in the top 2.6% of the state to get 90+ scaled, Specialist Maths top 5% for 90+- but maybe try the atarcalc if you want to know more legit scores.