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 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?**

**What is set and what can't be changed?**

**What are we in control of? Why are these variables?**

Through trial and error, we can find options:

The 3 different combinations can be shown in a bar model

8 |

X |
Y |

2 | 2 |

5 | 1 |

8 | 0 |