#### Answer

$h=\dfrac{A-2lw}{2l+2w}$

#### Work Step by Step

Subtract $2lw$ from both sides to find:
$A-2lw=2lh+2wh$
Factor out $h$ on the right side to find:
$A-2lw=h(2l+2w)$
Divide by $2l+2w$ on both sides to find:
$\dfrac{A-2lw}{2l+2w} = h
\\h=\dfrac{A-2lw}{2l+2w}$