Answer:
Let w be the width of the rectangle. The length would be 2w+3. The area of the rectangle would be w(2w+3)=189.
So 2w2+3w-189=0 Solving for w you get w=9 or -10.5. Ignoring negative value Width of the rectangle would be 9mm and length of the rectangle would be 21mm giving you the area 189 square mm.
Hope this helps:)
