#### Answer

$\frac{3\sqrt 2}{4}$

#### Work Step by Step

Rationalize the denominator by multiplying $\sqrt 64$ to the numerator and denominator.
$\frac{\sqrt 72}{\sqrt 64}\times\frac{\sqrt 64}{\sqrt 64}$
Simplify
$\frac{\sqrt 4608}{64}$
$\frac{\sqrt 2\times\sqrt 2304}{64}$
$\frac{48\sqrt 2}{64}$
$\frac{3\sqrt 2}{4}$
Answer: $\frac{3\sqrt 2}{4}$