The length of the blue rectangle is three, its width is two, and its area is six. In comparison, the green ratio has length six, width four, and area twenty-four.
So, the ratios of the lengths and widths are both 1/2, as 3/6=2/4=1/2. The ratio of the areas is 6/24=1/4. This makes sense, as since area is length times width, the ratio of the areas should be the product of the other two ratios.