So the manufacturers can make more money out of every box. It's not about the consumers, it's always about money.
Solve for w.
2=2(lw+lh+wh)
Flip the equation.
2hl+2hw+2lw=2
Add -2hl to both sides.
2hl+2hw+2lw+−2hl=2+−2hl
2hw+2lw=−2hl+2
Factor out variable w.
w(2h+2l)=−2hl+2
Divide both sides by 2h+2l.
w(2h+2l) / 2h+2l=−2hl+2 / 2h+2l
w=−hl+1/h+l
If the bases are the same then you can let the exponents be equal to each other. If the exponents are not the same then you will have to use logarithms to solve for x.