Final answer:
To find the constant of variation k in a direct relationship where x = 13 and y = 117, we substitute these values into the equation y = kx, resulting in k = 117 / 13, which simplifies to k = 9.
Step-by-step explanation:
When y varies directly with x, the relationship between the two variables can be represented by the equation y = kx, where k is the constant of variation. To find the value of k, we use the given values of x = 13 and y = 117 and substitute them into the direct variation equation.
y = kx
117 = k(13)
To solve for k, divide both sides of the equation by 13:
k = 117 / 13
k = 9
Therefore, the value of the constant k is 9, which corresponds to option a.