Complex sentence: As of the census of 2000, there is one household in the Indian reservation, consisting of a white woman between 25 and 44 and a white girl under 18; their median age is 31 years.
Split into simpler sentences: As of the census of 2000, there is one household in the Indian reservation; one adult and one child under the age of 18. One is under 18 and the other is between 25 and 44, their median age is 31 years.