Praise be to Allah, and may Allah’s peace and blessings be upon the Messenger of Allah, his family and his companions. Wa alaikum assalam wa rahmatullahi wa barakatuh. As to what follows: In response to your question, we say: If he fasts for twenty-nine then he has done what is incumbent upon him. However, if Eid is announced in that country when he has fasted twenty-eight days then he has to make up for the missing day after Eid. He has to follow the Eid of the people in the country that he has travelled to because the Prophet (peace be upon him) said, “Fasting (for the month of Ramadan) begins when the people start fasting, and Eid al-Fitr is on the day that the people stop fasting.” [At-Tirmithi (697)]