The answer is: x = 9, y = 6
A perimeter of a square with side a is:
P = 4a
Since sides of the square of the same, according to the image we have:
a = 3y
a = 2x
____
P = 72
p = 4a
4a = 72
a = 72 / 4 = 18
_____
a = 3y
a = 18
3y = 18
y = 18 / 3 = 6
_____
a = 2x
a = 18
2x = 18
x = 18 / 2 = 9