Expression to create even distances

Hi,

i want to add a control value (220) to the x-pos of my layer.

i want to define the x-positions of my layers automatically.

My master layer, containing the initioal x-pos, has its x-pos at 320.

Now for the next layers, with an expression, i each want to use the x-pos of the preceeding layer + add a control value of 220. So they distribute in x-pos by 220 distance between each other.

How is this to be done ?

Regards,

Frank