# >> K-12 >> Middle School

How to Figure Out a Variable in a Math Problem

In mathematics, a variable is a letter that represents an unknown quantity. Learning to solve a math equation with one variable is a basic skill that will help form the foundation of many more advanced skills later on, including creating and solving word problems. Although math problems with letters instead of numbers can look unfamiliar and a little scary at first, solving these equations is less complicated than it looks.

Pencil with an eraser
Paper

Instructions

- 1
  Add or subtract the same number to both sides of your equation so that your variable is alone on one side. For example, if your equation is 5x - 30 = -10, add 30 to both sides:
  
  5x - 30 + 30 = -10 + 30
  5x = 20
- 2
  Multiply or divide both sides of your equation by the same number so that your variable does not have a number in front of it. For example, divide both sides of 5x = 20 by 5.
  
  5x/5 = 20/5
  x = 4
- 3
  Check your answer by putting your solution in place of the variable in your original equation and making sure both sides are equal.
  
  5x - 30 = -10
  5(4) - 30 = -10
  20 - 30 = -10
  -10 = -10

Science Fair Project of Plant Gravity

Activities to Increase the Sense of Belonging in Middle School