What is an equation stating 2 ratios are equal?

An equation stating that two ratiOS are equal is called a proportion. It can be expressed in the form ( \frac{a}{b} = \frac{c}{d} ), where ( a ), ( b ), ( c ), and ( d ) are numbers or expressions. This means that the cross products are equal, so ( a \cdot d = b \cdot c ). Proportions are often used to solve problems involving similar figures, scaling, and comparisons.