Answer:
The perimeter of the shaded rectangle is 30 units.
Explanation:
Since we know that the side of each box is 3 units long we just have to find out how much sides of the boxes are used to create the perimeter of the shaded rectangle. If we look closely we will notice that the perimeter is consisted of 10 lengths of the side of the small box, and we also know that each one of those sides is 3 units long so we get that the perimeter is......
10 x 3 = 30