Let's get directly to the point

When two variable quantities have a constant (unchanged) ratio, their relationship is called a direct variation. It is said that one variable "varies directly" as the other.
The constant ratio is called the constant of variation.
The formula for direct variation is y = kx, where k is the constant of variation."y varies directly as x"Solving for k: (y = numerator; x = denominator)
Example: The weekly salary a woman earns, S, varies directly as the number of hours, h, which she works. Express this relation as a formula.