Answer:
1/9
Explanation:
I'm assuming the equation you mean is y = (x/9) -- if so, parentheses aren't really required.
The equation for the constant of proportionality is y=kx. So, we will want to find the value of k, which is the constant. The y and x variables are in both equations already, and there is only the 1/9, which is k.
Therefore, the constant of proportionality is 1/9. We can check this answer by putting 1/9 back into the equation. y = 1/9 (x) or y= x/9.