# Primary mathematics:Introduction to variables

A variable is any part of an equasion that replaces a number with something that can represent a number. For example, ${\displaystyle 5+E=14}$. In this case, ${\displaystyle E}$ is the variable. You may have seen this before as ${\displaystyle 5+}$__${\displaystyle =14}$. To solve a variable including problem with one step, you have to get rid of the first number. So for example, take
${\displaystyle x+36=45}$. To get rid of 36, we need to create ${\displaystyle -36}$. We also need to balance the problem on both sides. Therefore, the problem looks somewhat like this: . Now you solve the problem vertically. So
${\displaystyle 36+(-36)}$ equals 0, so we can get rid of that. Then we take ${\displaystyle 45-36}$ which equals ${\displaystyle 9}$. Therefore, ${\displaystyle x=9}$.