Answer
8 in by 20 in
Work Step by Step
$a = b*h$
$x = length$
$w = x/2-2$
$a = x*(x/2-2)$
$160 = x^2/2-2x$
$160*2=2*(x^2/2-2x)$
$320 = x^2-4x$
$x^2-4x-320=0$
$x^2-20x+16x-320=0$
$x(x-20)+16(x-20)=0$
$(x-20)(x+16)=0$
$x-20=0$
$x=20$
$x+16=0$
$x=-16$ (invalid since we can't have a negative length)
$w=x/2-2$
$w=20/2-2$
$w=10-2$
$w=8$
