### Unit 1: Variables and Variable Expressions

When most people think of math, they think of numbers. However, with this math course, you will be working with letters. In algebra, letters are used to represent numbers. These letters are called variables, because the numbers they represent may vary. For example, if you are paid $10 per hour, your salary can be expressed as 10×*h*, where *h* is the number of hours you have worked. You can change the number that letter *h* stands for according to your particular case in order to calculate your salary.

In this unit, you will learn that the properties of numbers apply to letters as well, and you can use them to work with expressions containing variables. One of the main skills you have to master in this unit is recognizing like terms, because you can add and subtract them as if they were numbers.

**Completing this unit should take you approximately 8 hours.**