In a city, the number of people living per cubic yard is 80. How many more people are in a city with 9000 cubic yards than a city with 6400 cubic yards?
The difference in cubic yards between the two cities is 9000-6400 = <<9000-6400=2600>>2600 cubic yards.
Since the number of people living in a city per cubic yard is 80, there are 80*2600 = 208000 more people living in a city with 9000 cubic yards than a city with 6400 cubic yards.
#### 208000