The elements in the table are in proportional.
Since for every 3unit increase in x, there is a 7 unit increase in y element. Thus, the elements in the table are in proportional.
When x=0 the value of y=0, when x=3 the value of y=7, and finally when x=6 the value of y=14.
The elements is in proportional because the next element is then defined as the multiple of two of the previous element.