Longitude and time calculation?

Question

if it is 7 am, on September 3rd, at 179 degrees WEST, what time and date is it at the same instant at 179 degrees EAST

thanks in advance!

Answer 1

This answer assumes that:
1.) You're at a point that straddles the GMT +/- 12 time zones. The Aleutian Islands are in GMT -10 at both longitudes. Russia is in GMT + 12 at both longitudes. Neither one crosses the date line at 180 degrees.
2.) You're not at a point that does change time zones, but does not cross the date line (like Tonga).

In that case, you simply subtract 24 hours when you go East across the date line, making it 7 AM Sept 2.

Answer 2

If you are at those coordinates, do the following:

Add 1 day, then subtract the hour, since you cross the International Date Line.

So it would be September 4th, 6am.