So I'm trying to figure out what your expression means:
X Position: You limited the object's horizontal movement or position on the x-axis to a minimum of half of the object's width and a maximum of the layout's width subtracting half of the object's width.
Min: Half of object's width = 38
Max: Layout's width (640) - 38 = 602
The object's movement is limited to a minimum of 38 and a maximum of 602 on the x-axis?
Sorry if I don't really understand. ;X