# What is an equation?

An

**equation**is a mathematical expression that contains an**equals symbol**.Equations often contain

**algebra**. Algebra is used in maths when you do not know the exact number in a calculation.Many professionals use equations every day, including air traffic controllers, architects, computer programmers and carpenters.

## What is an equation?

Here is an example of an equation:

*y + 5 = 10*

An equation has to contain an equals symbol (=). There will be a mathematical expression on either side of the equation, so you can think of an equation as having a **left-hand side** and a **right-hand side**.

Think of an equation as a set of weighing scales. You can put different quantities on the left or right-hand side, but to solve it, each side should be balanced.

An algebraic equation will always contain an **unknown**. This is represented by a symbol, for example *x*, *y* or *z*.

Solving an equation means finding the value of the unknown number by **performing the same operation** on each side.

When trying to calculate the answer to an equation, you should follow the order of operations represented by the acronym **BIDMAS**: **B**rackets, **I**ndices, **D**ivision, **M**ultiplication, **A**ddition and **S**ubtraction.

## Equations at work

Equations are used by many professionals. For example, air traffic controllers frequently need to calculate the minimum safe level for planes to fly at. To do this they use the equation:

*Minimum safe level (measured in feet) = 30 × (1013 - pa)*

(*pa* is the atmospheric pressure. This value can change daily, depending on weather systems.)

Engineers, architects and video-game designers all use equations in their work too.

## Equations quiz

Find out how much you know with this quick maths quiz!

## Where next?

Discover more about this topic from around Bitesize.