Question 1206984
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1. D ⊃ E
2. D v A
3. ~E                           / A

             |4. ~A       Assumption for Indirect proof
             |5. A v D         2, commutation
             |6. D           5,4, disjunctive syllogism
             |7. E           1,6, modus ponens
             |8. E & ~E      7,3, conjunction

9. A      lines 4-8  for Indirect Proof

Edwin</pre>