Add an hour to 11:30 a.m. to get 12:30 p.m.
Add an hour to 12:30 p.m. to get 1:30 p.m.
Add an hour to 1:30 p.m. to get 2:30 p.m.
Answer: Moscow is 3 hours ahead of Dublin
You can use military time and subtract.
11:30 a.m. = 11:30
2:30 p.m. = 2:30 + 12:00 = 14:30
14:30 - 11:30 = 3:00
The answer is the same 3 hours.
