Read the article and complete practice problems 1-10. This article further explains the meaning and usage of variables. It also provides many examples of using variables to represent quantities that you often encounter in the real world as well as exercises to practice choosing appropriate variables and writing variable expressions to describe situations on your own.

Click http://www.ck12.org/algebra/Variable-Expressions/lesson/Variable-Expressions-BSC-ALG/ link to open resource.