Ancient History:
Percentile: 90 (Top 10% of State; Approx. Top 1118)
Exam Mark: 90
Scaled Mark: 77.8
Percentile: 99 (Top 1% of State; Approx. Top 111)
Exam Mark: 97
Scaled Mark: 91.4
Legal Studies:
Percentile: 90 (Top 10% of State; Approx. Top 835)
Exam Mark: 90
Scaled Mark: 77.6
Percentile: 99 (Top 1% of State; Approx. Top 83)
Exam Mark: 97
Scaled Mark: 91.0
SORII:
Percentile: 90 (Top 10% of State; Approx. Top 355)
Exam Mark: 90
Scaled Mark: 80.6
Percentile: 99 (Top 1% of State; Approx. Top 35)
Exam Mark: 95
Scaled Mark: 92.6
SOC:
Percentile: 90 (Top 10% of State; Approx. Top 415)
Exam Mark: 88
Scaled Mark: 76.2
Percentile: 99 (Top 1% of State; Approx. Top 41)
Exam Mark: 96
Scaled Mark: 91.8
English Advanced:
Percentile: 90 (Top 10% of State; Approx. Top 2743)
Exam Mark: 90
Scaled Mark: 83.6
Percentile: 99 (Top 1% of State; Approx. Top 274)
Exam Mark: 95
Scaled Mark: 93.4
Exam mark is what you scored in the exam which is already moderated. The final scaled mark is what counts towards your UAI/ATAR. To achieve an UAI/ATAR of 90+, you'll need to be at the Top 5% range for Ancient History, Legal Studies and SOC as they are low scaling subjects. Top 10% for English Adv. and SORII will be fine.
Source:
http://www.uac.edu.au/documents/uai/2008_table_A3.pdf