# Solving Simple Equations

## Understanding Variables

To a mathematician or an economist, a **variable** is the name given to a quantity that can assume a range of values. In other words, the value of a variable can change or vary. In an equation it’s represented by a letter or
a symbol. Because economic models often consider cause and effect, variables are important. You will often be asked to consider a range of options that result from different variables. Below is a very simple example:

In order to understand the range of options, we might start with 0. What does *y* equal if ?

Now, let’s look at the same formula with different information. What does y equal if ?