Answer
$-2x^{4}$
Work Step by Step
We are given the expression $-\frac{16x^{5}}{8x}$.
We can simplify this expression by using the quotient rule, which holds that $\frac{a^{m}}{a^{n}}=a^{m-n}$ (where a is a nonzero real number, and m and n are integers).
$-\frac{16x^{5}}{8x}=(-\frac{16}{8})\times(x^{5-1})=-2x^{4}$