Given this information, your performance seems to be consistent with an ATAR between 79 and 81.
Mathematics Advanced and Business Studies appear to be your best-performing subjects, meaning that they are both likely to make a positive contribution to your ATAR. Because of this, you should ensure that you thoroughly prepare for the HSC exam of each subject, which will hopefully allow you to maintain this standard and maximise the contribution that both subjects will make to your ATAR.
The same can be suggested regarding Economics and Software Design and Development, although possibly to a slightly lesser extent. This could indicate that there are potential areas of improvement that you can focus on addressing as you continue to prepare for your HSC exams, which can enable you to solidify your overall performance in both subjects and in turn increase your chances of achieving your ATAR goal
On the other hand, your position in English Standard indicates that it is your lowest-performing subject. I definitely agree with SadCeliac that your preparations should primarily focus on this subject, since it may currently be limiting your chances of reaching your desired ATAR. Whether the same applies to Mathematics Advanced depends on whether the academic capability of your own cohort is comparable to that of last year's cohort. If so, then your rank in Mathematics Advanced could still potentially lead to a decent Assessment Mark. Of course, only you know your particular circumstances, and are therefore able to make an informed judgement accordingly.
Overall, an 83 ATAR is definitely within reach, although your performance in your HSC exams will be crucial in allowing you to achieve it.
I hope this helps!
