Remember,** a letter simply represents a number in algebra**.

Sometimes this may be set but sometimes it is up to you to work out what the number is worth.

Where a number can change it is called a **variable**.

In this activity, all of the answers must be whole numbers or zero.

**Example:**

**x + 3y = 8 **

What do we know? **That the total must be 8.**

What is set and what can't be changed? The **answer **is set and that **y needs to be multiplied by 3.**

What are we in control of? Why are these variables?** x and y are the variables because they could be several different numbers.**

Through trial and error, we can find options:

The three different combinations can be shown in a bar model

8 |

X |
Y |

2 | 2 |

5 | 1 |

8 | 0 |

Option 1: If x is 2, then 3y must be 6 so that they add up to 8. If 3y is 6, then y is 2.

Option 2: If x is 5, then 3y must be 3 so that they add up to 8. If 3y is 3, then y is 1.

Option 3: If x is 8, then y must be 0 so that they add up to 8.

Let's have a look at the questions now.