Not hard, visualize the locations on the globe and a pie with 24 slices. If you start work at 12, and you want to know when someone 2 slices West will start you add 2 to get 14. 2 slice East of you, subtract 2 to get 10.

Better than guessing what timezone the region picked when it spans multiple natural time zones, and whether they do or don't have time changes.

Ideally, you would be asking what time your specific colleagues start and end work, which could be quite different than the average of people who work in their country.