Rewrite the equation as
2lw+2lh+2wh=a.2lw+2lh+2wh=a
Subtract
2lh
from both sides of the equation.
2lw+2wh=a−2lh
Factor
2w out of 2lw+2wh.
2w(|+h)=w−2lh
Divide each term by
2(l+h)
and simplify.
.w=a−2lh2(l+h)
