#### Answer

$\frac{1}{2}$

#### Work Step by Step

Divide the inside of each radical with one radical over both of them.
$\sqrt{\frac{-10}{-40}}$
Simplify.
$\sqrt{\frac{-10}{-40}}=\sqrt{\frac{1}{4}}$
Pull the negative inside the radical into an imaginary number outside of the radical.
$\sqrt{\frac{1}{4}}=\frac{1}{2}$