Let for the 9^th term in the binomial expansion of (3+6 x)^n, in the increasing powers of 6 x, to be the greatest for x=3/2, the least value of n is…

Let for the $\displaystyle 9^{\text {th }}$ term in the binomial expansion of $\displaystyle (3+6 x)^{\mathrm{n}}$, in the increasing powers of $\displaystyle 6 x$, to be the greatest for $\displaystyle x=\frac{3}{2}$, the least value of n is $\displaystyle \mathrm{n}_0$. If k is the ratio of the coefficient of $\displaystyle x^6$ to the coefficient of $\displaystyle x^3$, then $\displaystyle \mathrm{k}+\mathrm{n}_0$ is equal to :