Question 925063
<pre>
1)  B -> D
2)  B v D
/   D
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3)  D v B               2       Commutation
4)  ~~D v B             3       Double Negation
5)  ~D -> B             4       Material Implication
6)  ~D -> D             5,1     Hypothetical Syllogism
7)  ~~D v D             6       Material Implication
8)  D v D               7       Double Negation
9)  D                   8       Tautology
</pre>


Hopefully that helps. If not, then let me know. Also, please point out the two rules that confuse you so I can go over them.


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