Your subjects are fine, as long as you study consistently..there's no reason why you can't achieve a good Atar
As for your choice between ancient history and business studies, do the subject that you are more interested in.
You won't be disadvantaged, just do a bridging course for Maths at uni and speak to the lecturers, there's always a way around maths
Worry about your Atar, not maths
Try a different way of studying for exams...and if your generally a good student who gets around 80%, talk to your teachers and they should give you a few tips
Re: b.economics usyd vs b.comm/law macquarie
According to RBA graduate opportunities website:
Cadets are third-year (or equivalent penultimate-year) students who intend to complete Economics or Finance Honours and who have attained a distinction average on the core subjects of their...
Even though you've done poorly in school assessments, forget about it and study for trials & HSC
You can't be screwed if you haven't done trials/HSC yet...as for your atar aim, as long as you study effectively, getting in the 70-80 region shouldn't be too hard
Even if you end up doing Commerce at University, legal studies won't be that beneficial
Just do the subject you are more interested in
As for Ext.1 maths, agree with OzKo, you'll be fine as long as you work consistently.
http://webcache.googleusercontent.com/search?q=cache:_hnoZI_8mRIJ:oconnorshamlet.weebly.com/uploads/7/8/6/7/7867305/intense_human_relationships_response_hamlet.doc+&cd=1&hl=en&ct=clnk&gl=au&client=firefox-a
Might help you with the question..
Overall, none of the business/commerce majors are difficult. It just comes down to your motivation & capacity to understand the concept instead of memorising/summarizing from lecture slides + textbook.
As for the high fail rate in Accounting, people just get lazy before final exam..
Considering there's no specifics by the original poster..
This should help with your question: http://mercury.webster.edu/westedou/financial_ratios.htmhttp://