Building upon this question, I would like to extend the unanswered question in the comments.
That is, do there exist $g,h: \mathbb{N} \rightarrow \mathbb{N}, y \in \mathbb{N}$, such that the following system holds? \begin{align*} (g \circ h \circ h )(y)= 3y \\ (h \circ g \circ h )(y)= 5y \\ (h \circ h \circ g )(y)= 7y \end{align*} Clearly using the provided method fails as these numbers no longer follow the same coincidental pattern ($4 = 2 \times 2$). However, we still have the equations $h(3y)=5h(y)$ and $h(5y)=7h(y)$ after plugging in $h$ to the second and third equations. As stated in the previous question the equations of the form $f(ax)=bf(x)$ only have one solution over the reals ($f(x)=cx^{\log_{a}b}$), but "many over the naturals". Is it still correct to say that these equations can not hold simultaneously? if so, why?