What defines a 'proportion' in mathematics?

A proportion in mathematics is defined as two ratios that have equal values. This means that the comparison between the two ratios results in the same relationship or fraction. For example, if you have the ratio of 1:2 and you find another ratio, like 2:4, both of these ratios simplify to the same value (1/2), thereby forming a proportion.

In practical terms, proportions are used to determine if two fractions are equivalent or to solve problems involving scale and comparison. The essence of a proportion lies in its equality, which allows for the cross-multiplication method to verify if two ratios are indeed equivalent.

The other options reflect concepts that are related to ratios or fractions but do not accurately describe the definition of a proportion. Understanding the nature of proportions is key to solving many mathematical problems involving ratios and comparative relationships.