Find y Using the Constant of Variation if y=12 when x=4 ; find y when x=12

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 ${\displaystyle y=kx}$, where ${\displaystyle k}$ is the constant of variation.

Solve the equation for ${\displaystyle k}$, the constant of variation.

Replace the variables ${\displaystyle x}$ and ${\displaystyle y}$ with the actual values.

Divide ${\displaystyle 12}$ by ${\displaystyle 4}$.

Use the formula ${\displaystyle y=kx}$ to substitute ${\displaystyle 3}$ for ${\displaystyle k}$ and ${\displaystyle 12}$ for ${\displaystyle x}$.