To the original writer who requested help:
Well...I guess if you like maths and currently doing well in it, I would recommend
Maths Extension l (3 units) in Year 11 and/or possibly Maths Extension ll (4 units) in Year 12.
Either way, they don't differ much in terms of the scaling ATAR.
Basically all Extensions courses scales well so if you want to, you could do English Extension as well but if you want to just do English Advanced, that's not too bad.
As for Economics and Business Studies in terms of the ATAR, I would pick Economics because Business Studies does scales you down though I am not so sure if Economics does scale up...
I'm quite sure it does.
Generally the harder subjects will scale relatively well.
Don't just pick the subjects just because of the 'scaling well' aspect, you also need to display certain interest in your subjects to do well in your subjects; even if you do poorly in your subjects, your ATAR for that subject will also drop...
I'm currently in Year 11 and my plan from beginning of Year 12 onwards is:
GET 100% IN EVERYTHING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!...........
Good Luck!!