chapter 29- abc soution

dear sir

firstly, i am not sure that, this is the right place to ask my specific question. if anoher place is more suitable then please inform me.

my question is that: solution is focused to recalculate the fixed costs via determining the effect of set up cost. the thing that makes me confused is, at the end how do we call this newly set up cost, is it a component of marginal cost (it seems to me like that) or fixed cost?

thank you in advance and with my best regards.