The formula for work ing out population density is to divide the number of people by the land area (PD = N/A). So in the example you need to work out the population density of a town of 30,000 people across a land area of 8km^2. So to get the population density divide 30,000 by 8 to give 3750 people/km^2. This tells you that there are 3750 people in every kilometre square of land area.
