How do I set the value to GUI offset?

How do I set the value to GUI offset?

if script.Parent[""..number.Value].Position.X.Offset > 40 then
                script.Parent[""..number.Value].Position.X.Offset = 40 ---It wont let me do this
            end

I cant use UDIM2.new because that involves Y axis variables, but this system works on more then one frame with different Y positions. And I can't use + UDIM2.new because it's not always the exact same value over 40 every time.