Cross multiplying is a way to solve an equation that involves a variable as part of two fractions set equal to each other. The variable is a placeholder for an unknown number or quantity, and cross-multiplying reduces the proportion to one simple equation, allowing you to solve for the variable in question. Cross multiplying is especially useful when you’re trying to solve a ratio.
- To cross multiply, you set up your equivalent fractions with your unknown.
- You multiply diagonally where you have two numbers (no variable).
- You divide that answer by the other number.
Here’s how to do it:
Cross Multiplying with a Single Variable
One More Step
(adapted from source)