Åk 6–9
3.1 Writing Algebraic Expressions
If you have gone through part 2 in this section, you have seen that you can express a problem in many different ways; in words, figures, tables, and finally algebraic expressions. You should even have learned moer about how to write algebraic expressions.

We begin with a figure and start with the earlier example about planting flowers.

Jasmine works in the summer as a landscaper.  One day she is asked to plant flowers in ten rows.  In every row there is to be three flowers.  How many flowers does Jasmine plant?

This is how the picture of the flowers looks:

If we express in words, this is what it looks like:
3 times the number of rows gives us the total number of flowers.

It can even be written as an algebraic expression:

Total number of flowers: f
total rows: r
number of flowers per row: 3

How do you think the algebraic expression for the number of flowers for the new planting would have looked?

We begin by looking at how many flowers there are in every row.
There are 4 flowers.

So the formula must be: f = 4 · r

f stands for the total number of flowers.
r stands for the number of rows.

The number of rows is 8. We replace the letter r with the number 8.
The number of flowers that are to be planted then becomes:

f = 4 · 8
f = 32

As you can see f and b each take different values, f and b are variables.