Physical measure allocation and sell or process further

and then sold for $$1\mathrm{.}50$ per board foot. No opportunity exists for processing Grade B lumber after split$-$off.

a$.$ How much joint cost should be allocated to Grade A and to Grade B lumber using the physical units method?

Grade $A$$$0$

Grade $B$$

b$.1.$ If Grade A lumber is processed further and then sold, what is the incremental effect on Oregon Forests' net income?

Processing further will result in an

Should the additional processing be performed?

Please answer all parts of the question.