A proportion is simply a statement that two ratios are equal.
Proportions can be written as;
![How to Calculate Proportion.](https://www.learntocalculate.com/wp-content/uploads/2020/08/proportion.png)
To determine if the ratios form a proportion, we can use cross products.
Example:
Determine if the ratios below form a proportion.
20:30 = 2:3
![How to Calculate Proportion.](https://www.learntocalculate.com/wp-content/uploads/2020/08/proportion-2.png)
Thus, the ratios form a proportion.