If I have the surface area of a box, its width and its length but not height, how can I determine the height?

Answer 1

2(wl + wh + lh) = surface area
2wl +2wh + 2lh = SA
2wh +2lh = SA - 2wl
h(2w + 2l) = SA - 2wl
h = (SA - 2wl)/(2w + 2l)

apparently you know w, l, and SA, all the stuff on the right side.

Answer 2

Thank you.