Arnison AFM Pre-June 2023 Mock

Q2b Arnison
(b) Estimate the percentage gains to the Arnison Co and the Birks Co shareholders under each of the two offers?
1. A cash offer of $2.40 per share.
2. A share for share exchange, offering 4 shares in the combined company in
exchange for every 5 shares in Birks Co.

My question is related how should we approach this question? Probably, to find the percentage change in pre and post acquisition MV of shares of both Arnison and the Birks shareholders?

For the share for share exchange my approach works. Just, some key highlights.
I find the MV per share of the combined company – 3.45$ per share (510m/148m shares). Post acquisition MV of target share 2.76$=3.45$*4/5. As a result, the calculated percentage gains are the same as with the examiner answer.

However, in cash offer, this MV shares approach does not work.
The examiner’s approach is different. He calculates the synergy gain (which is understandable) and allocates it between Predator and Target shareholders (not very clear).

Please clarify, what exactly we are doing in the cash offer scenario? It seems, that this is not MV of shares percentage change evaluation.