If $\log_6 (4x)=2$, find $\log_x 27$. Express your answer in simplest fractional form.
We begin by solving for $x$ from the first equation $\log_6 (4x)=2$. Expressing this in exponential form, we find that $4x=6^2$, giving us $x=\frac{6^2}{4}=9$. After plugging this value of $x$ into $\log_x 27$, we end up with the expression $\log_9 27$. Since $27=(9)(3)=(9^1)(9^{\frac12})=9^{\frac32}$, we see that $\log_9 27=\boxed{\frac32}$.