If 4/5 of a population of a certain town is considered to be middle class and the population of the town is 2000 how many people are considered middle class

First, you would need to create an equation for this problem.
=

Next, you would cross multiply. 
5x = 8,000

Now, all you would have to do is isolate the x. To do this, you would divide both sides by 5. 
x = 1,600

1,600 people are considered middle class. 

I hope this helps!