have this calculation happening as a first calculation and then after that we can do this calculation which we know from filtering this is giving us the quantities we saw in filtering because everything happening here so we did in filtering we know what those quantities are going to be then how about these here what can we reorganize here to make this the summations kind of move in well it's going to be similar to what we have happening here x0 is the furthest out in the chain and so it gets on the most inner side simply