Los Angeles (LA) is in the Pacific Time Zone (PT), which is UTC-8. Sydney, on the other hand, is in the Australian Eastern Time Zone (AEST), which is UTC+10.
To convert the time from PT to AEST, we add the time difference between the two time zones. In this case, the difference is UTC+10 - UTC-8 = UTC+18.
Now, to calculate the time in Sydney when it is 4pm in LA, we add UTC+18 to the given time.
4pm PT (LA) + UTC+18 = 10pm AEST (Sydney)
Therefore, when it is 4pm in Los Angeles, it is 10pm in Sydney.