lol here we go again. Scaling is based on the performance of the candidature of a given year, and it is therefore impossible to predict how the subject will align and scale. Typically, Extension Maths aligns very well; in 2002 a mark of 30/84 would get you a 60-70 aligned mark.
yes thats for extension maths. it's hard to tell what the aligning will be like this year, however if the paper was the same difficulty or harder than 2001's paper, then you can expect a high 40s mark
Again I give the standard disclaimer that the aligning process changes from year to year so it's impossible to predict. Based on the 2001 paper, a 50/84 would have gotten you a 45/50.