Hey I had kinda the same problem as you, except my subject was methods. Hated it, have no idea why I continued it into year 12.
Basically I did no work for teh subject whats so ever, except going to class.
Managed to get 25 which too me is pretty good considering I didn't do one of the exams.

Btw I got a 25 with 3 D's.
My reasoning to myself was that I know I have no chance in this subject, so I neglected it and worked on my other subjects instead, which I knew I had a better chance of increasing my study score.
Also it did help that a did a 3/4 in year 11.
Did you do a 3/4 in year 11?
It is hard just knowing you are neglecting a subject but for me it was a calculated decision.
No matter how many subjects you do you are going to have to work hard. Just do the work, get help from your teachers as soon as can when you don't understand something and ask questions here on AN.
everyone here is very helpful and want to help others achieve to the best of their ability.