Man co Past paper question transfer pricing

Hi Dear Tutor, I have questions. Question a) Briefly it is calculated 37-20 and 17 will be incremental loss but I would like to see it in a wider picture scenario and I became stuck in doing it. (When I watched your lecture on transfer pricing your way is really logical and understandable. Usually you showed group profit and then each division separately,overall each division's seperate profit amounted to the group profit.) I just tried to do it in that way but I just became stuck and the calculation is showen in the brief way. As a group Selling price-----------96 Marginal cost --------(20) Own marginal cost (30) profit---------------------46 If division L sell to internal customer Selling price------40 Internal marginal cost (24-4) profit============20 If division M buys Internally Selling price---------------96 Transfer price--------------(40) Own Marginal cost----------(30) Profit------------------------26 So 26+20=46 If the division M buys from outside then incremental loss for the company will be 17=46-29 but the department M will lose 3$ (29-26) profit when buying from outside supplier? Selling price---------96 Marginal cost own--(30) Marginal cost division (37) profit===========29 Do you think my way is good and logical?I know it does not to calculate in such a long way but as I mentioned above i want to see it in a wider picture scenario.