Suggest you look at your textbook or course notes for solutions. For simplified understanding, some textbooks would replace "transaction cost" with "agent cost". However, for business case analysis, it is not that simple.
Real world situation is even much more complicated and almost impossible to calculate. A sense of cost is enough (normally less in money terms).

So are you saying the transaction costs and agent cost overlaps each other in term of vertical integration?

btw, can you recommond a textbook including these two costs theories?

thanks a lot

I am so sorry that I am not good at related economics. And I don't know what your subject and its level is in university.
I meant with my previous response, there can be quite a lot of definitions of "transaction costs" and "agency costs" depending on academic subjects and levels. Some are wider, some narrower, some disjoint and some overlap. So it could be careless to say anything about a serious matter. This is the reason I suggested you just concentrate on your textbook or course notes. I also meant, theory and prctice with economics generally find themselves at odds.

Also sorry for not writing in Chinese. I don't have comfortable Chinese language software.

never mind, it's very helpful. thanks again.

David Besanko,Economics of Strategy,Chapter 3,which explained all these concepts and cases.Recently, I am trying to complete my assignment related to agent cost -_-// ...