Ratio
Ratios can be simplified. In the school example, there were 20 teachers to 500 pupils. If we divided the children up into equally sized classes, then each of the 20 teachers' classes would have 25 pupils. That means that for each teacher there are 25 pupils, or alternatively, the teacher-to-pupil ratio is 1:25. Another way to work this out is to divide both sides of the ratio 20:500 by 20. Note that 20:500 is the same as 1:25. Just like there are different ways of writing a fraction (for example ), there are different ways of writing one ratio.