What is a variable? A variable in math is our unknown. We usually represent this unknown with a letter or a symbol. For example, in the following equation, the variable is the letter c.
c + 2 = 5
To solve for this I am going to use the inverse operation. Inverse means opposite. The operation I currently have is addition. The opposite of addition is subtraction. I want to get the letter c by itself, or isolate it. To do that I will use subtraction in this case. I will subtract 2 from both sides to get c by itself.
c + 2 = 5
c - 2 = 5 - 2
c = 3
I can check my answer by substituting my answer for the variable.
3 + 2 = 5
If I get the right answer, then I know the value of the variable.
Watch the following video about how to solve equations with a variable.