Carol has 2 1/2 strawberry pies left over from a family reunion. if each serving is 1/8 of a pie how many servings does she have?

The first thing you do is to make 2 1/2 a top-heavy fraction: 
2 1/2 = 2 X 2 + 1 = 5/2

Now it's just division with fractions. 
5/2 / 1/8

All you have to do is switch the 8 and the 1 around and then change the divide sign in a X: 
5/2 X 8/1 = 
40/2 = 20/1. 

Carol has 20 servings of strawberry pie left.