I think your screen size will likely vary between phones.
You should use a method to access the screensize.
Probably subtract a buffer (say 200 pixels) from each side of the screen size (e.g.
1920 - 2*200)
Divide the remainder by 5, as you want 4 ropes (so 5 gaps between them)
B = Buffer , G = Gap, | = Rope
B G | G | G | G | G B
'Screen Space to World Space' transformation to transform co-ordinates for the rope positions into world space coordinates at which they can be placed.
Rope n Position = BufferSize + n*GapSize