. \$\frac{12n^5}{36n}\$

$. \$\frac{12n^5}{36n}\$$

Simplify the fraction of the coefficients $\frac{12}{36}$.
$\frac{12}{36}=\frac{1}{3}$

Use the rule of exponents $a^m\div a^n = a^{m - n}$ for the variable $n$. Here, $n^5\div n=n^{5 - 1}=n^4$.

Multiply the simplified coefficient and the simplified variable part.
$\frac{1}{3}\times n^4=\frac{n^4}{3}$

$\frac{n^4}{3}$