Question 1112733
1) A v B
2) B > (A v D)
3) ~D

Conclusion: A
========================
<pre>
1.  AvB     Premise   
2. B—>(AvD) Premise
3. ~D       Premise
4. :: B     Assumption, begin conditional proof (CP) - Case 1
5. :: AvD   4,2  Modus Ponens (MP)
6. :: A     3,5  Disjunctive Syllogism (DS)
7.  :: ~B   Assumption. Case 2
8. ::  A    7,1    DS
9. A        6,8   Proof By Cases (PBC), end of CP,  (A is true under no assumptions)