For June’13, the premium of the share for share exchange calculate base on Acquirer’s current share price, but in Dec’12 the premium calculate based on expected share price of combined company.
Same goes to the bond value, for June’13, the bond value per share is the par value, but in Dec’12 the bond value per share is calculated based on market value of bond.
It depends whether you are looking at it from the point of the acquirer (because the acquirer will be able to estimate the future share price of the combined company), or from the point of the seller (because the seller will only know the current share price of the acquiring company).
If the question does not make it clear, then state your assumption and you will get the marks either way.