Unit A6.6

Modelling using linear equations.

The following notes will help you to construct linear equations:

1. Represent the quantity to be found by a symbol (x is usually used).

2. Make up the equation that conforms to the given information.

3. Make sure that both sides of the equation are in the same units.

The equations can then be solved using the previous techniques.

e.g. A library buys 50 books. Some cost £5 and the others cost £7. If the library spent £290 in all, how many books costing £5 did it buy?

Let x be the number of books bought for £5 each.

Then 50 - x is the number of books bought for £7 each.