Determine whether each linear function is a direct a variation. If so, state the constant of variation. If not, explain why notI need help for number 6

In direct variation function, variables x and y are related by the next formula:
y = kx
where k is the constant of variation.
Isolating k for the above formula, we get:
k = y/x
Computing y divided by x with the values of the table:
[tex]\frac{5}{10}\ne\frac{6}{11}\ne\frac{7}{12}\ne\frac{8}{13}[/tex]Given that all the quotients are different, then the linear function is not a direct variation