Answer:
5 1/3 cm
Explanation:
If the perimeter of the small square is 2/3 of the perimeter of the large square, then the sides have that same ratio:
(x +4) = 2/3(3x +4)
x +4 = 2x +8/3
4/3 = x . . . . . . . subtract (x+8/3)
Then the side length of the small square is ...
4/3 +4 = 5 1/3 . . . cm