If there are four whole boxes, here's how the picture could be interpreted incorrectly.

"There are 5 rectangles total for each whole box, 3 of which are filled in. When there are four such boxes, there are 20 rectangles total with 12 shaded in. Hence "

This interpretation is incorrect because we are multiplying the number of shadedandunshaded boxes by 4. and so a true interpretation of the picture would be