imo either UTS or Wollongong uni, UNSW has a very good reputation but i think its overrated, i know a few people who went there and then transferred to another uni because they thought it wasn't that great, none of them were doing engineering though.
the big one: N=((m(1+r)^n)-1)/r(1+r)^n is used to find the future value when the question gives you the contributions but not the future value.
if the future value is given but not the contribution use N=a/(1+r)^n
m is the symbol for contribution from future value formula and a is future value...
It depends on what uni you go to, i live near Woollongong uni and i know you only need an 80 for engineering and no pre requisite, their also the second best engineering uni behind UTS so its worth having a think about them before repeating.