Looking at the image, the width of the rectangle is 7 small rectangles and the length is 9 small rectangles, therefore the area of 1 square unit is equal to 9 * 7 = 63 small rectangles.
From these small rectangles, an area of 5 * 4 = 20 small rectangles is shaded.
Therefore the shaded area is calculated as:
[tex]\frac{20}{63}\cdot1\text{ square unit}=\frac{20}{63}\text{ of a square unit}[/tex]
