#### Answer

$\frac{\sqrt 15}{x}$

#### Work Step by Step

Rationalize the denominator by multiplying $\sqrt x^3$ to the numerator and denominator.
$\frac{\sqrt 15x}{\sqrt x^3}\times\frac{\sqrt x^3}{\sqrt x^3}$
Simplify
$\frac{\sqrt 15x^4}{x^3}$
$\frac{x^2\sqrt 15}{x^3}$
$\frac{\sqrt 15}{x}$
Answer: $\frac{\sqrt 15}{x}$