A <u>proportion</u> is simply a statement that two <u>ratios</u> are equal. In problems involving proportions, we can use cross products to test whether two ratios are equal and form a proportion. To find the cross products of a proportion, we multiply the outer terms, called the <u>extremes</u>, and the middle terms, called the <u>means</u>.
Consider given proportion

Here, 2 and 30 are the extremes and 3 and 20 are the means.
Answer: the means are 3 and 20.