How do I Anchor middle

How do I anchor in middle of screen or relative (like 10% left of center)?

you can use, or do some maths with the following values:

ViewportBottom(layer)

ViewportLeft(layer)

ViewportRight(layer)

ViewportTop(layer)

Return the viewport boundaries in layout co-ordinates of a given layer. Not all layers have the same viewport if they are parallaxed, scaled or rotated separately.

from the manual

Thanks, solved