It's 9 total:
http://www.mq.edu.au/future_students/undergraduate/bonus_points/academic_advantage/
"
You can receive a maximum of nine bonus points if Academic Advantage is combined with other access schemes such as uniTEST or the Lighthouse Scheme."
But...
You might as well try out for B commerce UNSW or (B economics)
It's possible for you to get into a course with higher cut-off... but not in a course with lower cut-off.
What I mean is: Since different universities assess disadvantages differently, it is possible for you to get into UNSw... but not Macquarie.
E.g.... My 2011 ATAR was 86.9... UNSW med science cut-off was 95.10...... USYD med science was 92.10.
USYD gives 5 bonus points max (at the time when I applied to UAC... it wasn't possible to combine subject bonus with EAS for this uni... I think it is still the same now)
UNSW gives 10 EAS and 5 subject bonus.
So, my selection rank was 86.9+5 = 91.9 for USYD.... 86.9+15 = 101.9 for UNSW. (I got into UNSW med science, my 1st preference. But I wouldn't have made it into USYD med science because 5 bonus points were not enough.)
Normally, one would expect it to be easier to get into a course with lower ATAR cut-off... but... paradoxical situations can happen.
If you get 81 ATAR.... and...
if you have the "most number" of disadvantages or disadvantages of "highest severity"... and that you get the 5 subject bonus....
that's 81 +15 = 96 (just below the cut-off for unsw commerce 96.30... but above unsw economics 94.30)
Hopefully I scared you into considering other unis as well.