$$heightoftriangle=8squares$$

$$lengthoftriangle=10squares$$

$$=>Areaoftriangle=\frac{8\times 10}{2}=40$$

By counting the unshaded squares, we will know that:

$$unshadedsquares=28$$

$$=>shadedsquares=40-28=12$$

$$\therefore \frac{shaded}{unshaded}=\frac{12}{28}=\frac{3}{7}$$