I am in the same situation as you. It sucks that general maths and standard english scales ridiculously low. I didn't take scaling into considerations when choosing subjects as people told me "choose subjects that you enjoy" -.-
Anyways, I think it is possible, but definitely you will need to work really hard. For general maths, you won't get scaled that bad if you reach the 90s so you just need that extra few marks.
Time is running short so my best advice is focus on the subjects you are good at and you know you will do well in. Don't waste time on subjects that you may or may not do good in. Work with your advantages not against it.
Anyways goodluck! =)