Complex sentence: The people who live on the island issues an ad in a national newspaper: they seek a family with two children old enough to join the school, and promise a job in the tourism-industry if the family chose to live there.
Split into simpler sentences: The people who live on the island issues an ad in a national newspaper: they seek a family with two children old enough to join the school. They promise a job in the tourism-industry if the family chose to live there.