Answer
$SA = \frac {240}{x} + 2x^2$
Work Step by Step
Volume of a box = $V = lwh$
The base is a square, so $l = w$
The volume is given as 60 cubic feet
Surface Area is: $SA = 4 * wh + 2 * base$
$SA = 4wh + 2w^2$
So $V = 60 = w^2 h$
Thus $h = \frac{60}{w^2}$
Substitute h into the surface area equation
$SA = 4w \frac{60}{w^2} + 2w^2$
$SA = \frac {240}{w} + 2w^2$
The problem asks for w to be x, so:
$SA = \frac {240}{x} + 2x^2$
