In this activity, all the answers will be ** whole positive numbers **or

**.**

*zero*

An equation with two variables involves two numbers which must be found.

*"I think of two numbers.*

*When I double the first and add this to the second, I get 8."*

In written algebra, when * a *and

*stand for two numbers, we can change the problem above into this:*

**b**

**2a + b = 8**

This means that* twice a* added to

*must come to 8.*

**b*** a and b* are whole positive numbers or zero.

What could they be?

If a is 0, *b must be 8*

If* a is 1, b must be 8 - 2 = 6*

If *a is 2, b must be 8 - 4 = 4*

If* a is 3, b must be 8 - 6 = 2*

If* a is 4, b must be 8 - 8 = 0*

The results can be shown in a table:

a | b |
---|---|

0 | 8 |

1 | 6 |

2 | 4 |

3 | 2 |

4 | 0 |

There are five** **solutions.

Shall we have a go at this in some questions now?