[benjaln]

I'm having some trouble understanding this. In my organic lab, we did an experiment where we synthesized a triblock copolymer (delta-decalactone, L-lactide, with benzene dimethanol as the initiator) and now I have to figure out how to calculate the number average molecular weight of that polymer, or the Mn. We haven't gotten to polymers in lecture, so I have no idea how to do this, and everything I've looked up hasn't been helpful.
I understand it has to do with the molecular weights of the monomers and initiator, as well as the number of moles of each that I used in the synthesis, but I'm not sure what to do with this info. The assumption is that the polymer is symmetrical. Here is an image of the final polymer: