Question 198164
{{{VolumeOfBox = Length * Width * Height}}}
{{{Length = Width + 2}}}
{{{Height = Width - 1}}}

{{{VolumeOfBox = Length * Width * Height}}}
{{{V = (W+2) * W * (W -1)}}}
{{{140 = (w^2 + 2W) * (W-1)}}}
{{{140 = W^3 - W^2 + 2W^2 - 2W}}}
{{{0 = W^3 + W^2 - 2W - 140}}}

No go here and plot that to find the zeros
http://www76.wolframalpha.com/input/?i=0+%3D+W^3+%2B+W^2+-+2W+-+140

Looks like 5 is the only real solution