In the table below, y varies directly with x, Which equation best describes the data?

To determine which equation best describes the data, we need to check if y varies directly with x. In other words, we need to see if the ratio of y to x is constant for all the data points.

Let's calculate the ratios for the given data:

For the first data point, when x = 18 and y = 6, the ratio y/x is 6/18 = 1/3.
For the second data point, when x = 3 and y = 1, the ratio y/x is 1/3.
For the third data point, when x = 9 and y = 3, the ratio y/x is 3/9 = 1/3.

Since the ratios are consistent and equal to 1/3 for all the data points, the equation that best describes the data is y = 1/3x. Therefore, the correct answer is:

y = 1/3x