When two variable quantities have a constant ratio, their relationship is called a direct variation. It is said that one variable varies directly as the other. The formula for direct variation is , where is the constant of variation.
Solve the equation for , the constant of variation.
Replace the variables and with the actual values.
Dividing two negative values results in a positive value.
Use the direct variation model to create the equation.
Substitute the value of into the direct variation model.
Simplify the result to find the direct variation equation.