If he travels during Ramadaan to another country that started the fast at a different time, how should he fast?

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Check below answers in case you are looking for other related questions:
They fasted then they went back to their homeland where Ramadaan had not yet begun
Every person who is resident in a country is obliged to start and end the fast with its people

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Related Answers:
Ramadan began when he was in another country but he did not fast with them because he was travelling. Does he have to make up that fast?
We should rely on sighting of the moon, not on calculations
The Muslims should cooperate in sighting the moon and informing the authorities
They fasted then they went back to their homeland where Ramadaan had not yet begun
Every person who is resident in a country is obliged to start and end the fast with its people

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