Chapter 5 - Section 5.2 - Negative Exponents and Scientific Notation - Practice - Page 349: 9

$27x^{12}$

$\frac{(3x^{5})^{3}x}{x^{4}}=\frac{3^{3}\times(x^{5})^{3}\times x}{x^{4}}=\frac{27\times x^{5\times3}\times x}{x^{4}}=\frac{27\times x^{15}\times x}{x^{4}}=\frac{27x^{15+1}}{x^{4}}=\frac{27x^{16}}{x^{4}}=27x^{16-4}=27x^{12}$