Ask yourself this question:
Do you actually think you can go well in 2u though. 15% isn't very good, and it's the beginning of the year 12 year which means that it's only going to get more difficult from here on. You will need to put in a lot of work to catch up, and if you find that you actually can't do 2u maths even with all the effort you have put in, then it will be too late to catch up in general.
Alternatively if you move to general, you will have to put effort in to catch up. I've seen people drop from 2u maths to general and who fail general, simply because they haven't put in the effort to learn the content. Yes it is considered the easier course, however it's also very different. So you will need to put in the effort to do well.
Whether you decide to stay or decide to move, you will need to put in a lot of effort if you want a good maths mark
Okay. It's just I'm not sure if I will need mathematics for uni as "assumed knowledge". But if I drop to general, would it be harder if I do a bridging course?
At the moment I want to do Bachelor of Health Science at University of Sydney and major in psychology. Currently doing: studies of religion 2, English standard, community and family studies, senior science, biology and mathematics
With HSC, you want to think about what combination of subjects will help you achieve the best mark that you can possibly get.
Although it's good to consider what may be helpful for your uni course, if you don't get the atar for the course you want, then all that 'consideration' will be for nothing.
Bridging courses are designed for people who dropped maths in year 10 or are doing general, so if you did a bridging course, then you'd be fine.
Also, a BHS doesn't have any assumed knowledge, although I think chemistry and possibly bio may be recommended.
However, if you're thinking about transferring later on to something like physio or exercise physiology, then 2u would be really helpful