what time is 3am PST in Brisbane Australia?
Time Zones in Australia on a map - makes it real easy
Your question is not clearly worded.
If you mean -- what time is it in Brisbane, Australia, when it is 3 a.m. in the United State's Pacific Time zone (PST) ... then the answer is 9 p.m. (on the same day).
9pm the same day (18 hours ahead in other words). Brisbane is EST Australian time, no daylight savings.