Complex sentence: The population density was 1.4 people per square mile (0.5/km²), with 12 housing units at an average density of 2.0/sq mi (0.8/km²).
Split into simpler sentences: The population density was 1.4 people per square mile (0.5/km²). There were 12 housing units at an average density of 2.0/sq mi (0.8/km²).