General mathematics is actually the easiest subject I did. Just understand the formulas and its a guaranteed Band 5. I got a raw mark of 85 (Which was lower than I expected as I did all past papers with marks of 88+). The raw mark of 85 gave me a HSC mark of 93. My ATAR was 83.70 with general mathematics being my best subject. My friends who also did Generals maths received a hsc mark of 90 and got an ATAR of 95.

So basically, if you do well in general mathematics, there is no worry.