What is the definition of means and extremes?

In mathematics, particularly in the context of proportions, the terms "means" and "extremes" refer to the four terms in a proportion ( \frac{a}{b} = \frac{c}{d} ). In this case, ( a ) and ( d ) are called the extremes, while ( b ) and ( c ) are the means. The relationship signifies that the product of the means equals the product of the extremes, or ( a \times d = b \times c ). This concept is fundamental in solving problems involving ratiOS and proportions.