MATH PROPORTIONS, also known as ratios, are a mathematical concept used to compare two or more values. They are expressed as a fraction, with the numerator representing one value and the denominator representing the other. Ratios are used to compare quantities in different units, such as miles to kilometers, or to compare different parts of a whole, such as the number of boys to girls in a classroom. Ratios can also be used to solve problems involving proportions, such as finding the missing side of a triangle when given two sides.