Answer:
Proportion
Step-by-step explanation:
A proportion is an equation which states that two ratios are equal.
A proportion relates two parts of an equation, these can be two ratios, an example of proportion is as follows:
, or

This examples are proportions since both sides of the equation have the same value (in the first case 0.5 and in the second case 0.33..), in other words: the ratio 1:2 and 2:4 are the same, and the ratio 3:9 and 1:3 are the same.
When a ratio is known, a proportion can be found by multiplying or dividing both elements of the initial ratio by the same number.