# Ratio

A ratio is used to compare two quantities. The quantities should be in the same units.

### Example

A farmer has $$3$$ cats and $$7$$ dogs.

Write down the ratio of cats to dogs and the ratio of dogs to cats.

Cats : Dogs = $$3 : 7$$

Dogs : Cats = $$7 : 3$$

Question

The same farmer also has $$85$$ sheep and $$15$$ cows.

Write down the ratio of cows to sheep in its simplest form.

cows : sheep = $$15 : 85$$

$$15$$ and $$85$$ are both divisible by $$5$$

$\frac{{15}}{5} = 3$

$\frac{{85}}{5} = 17$

So $$15 : 85 = 3 : 17$$