The closest exams should be prioritised. In your case, you should place your focus on your English and Modern History HSC exams from today until the exam date. If you feel that you are still able to find some additional study time after preparing for these subjects each day, you may spend that time to slowly start preparing for the following exam. Your next HSC exam is maths, meaning that any additional time you find after you prepare for English and Modern History could go towards revising concepts and completing practice material (such as textbook questions and past exam papers).
Once you finish your English and Modern History exams, you will have plenty of time to build on your preparations for your next exam. This is where you can allocate much more time towards revising concepts (especially those that you may find most difficult) and completing practice material. Similarly, if you find additional time that can be spent on preparing for another subject, you could do the same here. Here, this subject would be Business Studies. The good thing about this subject is that preparing for the HSC exam entails a clear and fairly straightforward process:
- Go over the syllabus, ensuring that you know the topics as well as their respective dot points
- Revise the content. If you find that there is any aspect that you are not fully confident with, you should seek clarification as soon as possible.
- Ensure that you are familiar with a range of case studies in order to ensure the highest possible quality Section IV response.
- Complete past exam papers so as to make sure that you are able to apply your knowledge of the content to actual exam questions
Once you complete your maths HSC exam, this is when you can emphasise the above process in the next five days leading up to your Business Studies HSC exam. If you find additional time (which I believe you might), Economics will be the subject to allocate that additional time towards until you complete Business Studies after you which you can become fully focused on your Economics HSC exam.
I hope this helps!