we have
\(s=2(lw+lh+wh)\)
Solve for w means that clear variable w
\(s=2(lw+lh+wh)\\s=2lw+2lh+2wh\)
Group terms that contain the variable w, and move the other terms to the opposite side of the equation
\((s-2lh)=(2lw+2wh)\)
Factor the variable w
\((s-2lh)=w(2l+2h)\)
Divide both sides by \((2l+2h)\)
\((s-2lh)/(2l+2h)=w(2l+2h)/(2l+2h)\)
\(w=(s-2lh)/(2l+2h)\)
therefore
the answer is
\(w=(s-2lh)/(2l+2h)\)
