Greatest Term in Expansion

Let for the $9^{th}$ term in the binomial expansion of $(3+6x{)}^n$, in the increasing powers of $6x$, to be the greatest for $x=\frac{3}{2}$, the least value of $n$ is $n_0$. If $k$ is the ratio of the coefficient of $x^6$ to the coefficient of $x^3$, then $k+n_0$ is equal to: