Calculating Center of Mass: Xi & Yi for Statics

[Yarnzorrr]

Ive been given this table in a lecture (attached) and I'm not sure what they're using to fill in the columns of Xi an Yi, it looks like it should just be half of each section in Yi, but that is not the case in Xi, can anyone please explain this to me.

Thanks =)

 

[Yarnzorrr]

Oh its okay I understand, you have to include the entire thing and not just the individual sections.

ie.
xi (1) = 40/2 = 20
xi (2) = 300/2 + 40 = 190
xi (3) = 20/2 + 300 + 40 = 350