#### Answer

$h = \frac{8}{3w}$

#### Work Step by Step

Since length is twice the width we can create a variable for length $l$ and set it to $2w$ where $w$ is the width.
$l = 2w$
Knowing that the formula for the volume of a box is $V = lwh$, we can plug in the given $8ft^{3}$ for the volume and $2w$ for the length. This gives us
$8ft^{3} = 3wh$
and since we want the height in terms of the width, we just have to isolate h on one side of the equation by dividing $3w$ over to the other side giving us
$h = \frac{8}{3w}$
as our final equation.