#### Answer

$\frac{8}{9}$

#### Work Step by Step

We never can divide by a fraction. Rather, we must multiply the first fraction by the reciprocal of the second fraction. Because the reciprocal of 9/10 is 10/9, we obtain:
$\frac{4}{5}\times \frac{10}{9} = \frac{40}{45}=\frac{8}{9}$.