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Course Contents (16)
Creating Expressions - IntroductionDescription: Create expressions using a letter to represent a variable or changeable quantity.

## Objective:

Purpose is to learn how to create expressions using a letter to represent a variable or changeable or unknown quantity

## Help on this Topic:

Example. Paul makes 10 euro per day plus 8 euro for each hour that he works.

So if he works for 3 hours he will make:
10 euro  +  8 times by 3
So if he works for 6 hours he will make:
10 euro  +  8 times by 6
You can see that part of this ‘formula’ does not change and part of it does change.
The part that changes is ‘Variable

The expression for how much he works is :
10 euro  +  8 times by (the variable number of hours worked)
When we have a variable number of hours we can use a letter to ‘stand in’ for that unknown number of hours.
Let ‘n’ be the letter we choose for ‘the Number of hours’

The expression for how much he works is :
10 euro  +  8 times by (the variable number of hours worked)
Or in short hand  :
10 + 8n

Creating and using Expressions

An expression is a combination of variable and constant values.

Example Expressions

Using the variable ‘n’ to represent how many hours John works for on a given day, create an expression for how much he earns if he is paid 10 euro per day plus 9 euro per hour.

10 + 9 times how many hours he works

= 10 + 9n

Example Expressions

If a toy weighs ‘w’ grams and 12 toys are contained in a box which itself weighs 20 grams, how much does the box of toys weigh?