Answer
4 inches
Work Step by Step
We know that the perimeter is 2*length+2*width. We use the image for guidance and the given fact that the perimeter is 102:
$102=2(20+2x)+2(15+2x)$
We solve for $x$:
$102=40+4x+30+4x$
$102=70+8x$
$32=8x$
$x=4$
So the width of the strip is 4 inches.
