Question 1109316


<pre>
1.  P & Q 
2.  P -> R     / R & Q

3.  P            1, simplification
4.  R          2,3, modus ponens
5.  Q & P        1, commutation
6.  Q            5, simplification
7.  R & Q      4,6, conjunction  

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1.  (P v Q) -> R    /  ~R-> ~Q

2.  ~R -> ~(P v Q)  1, transposition
3.  ~R -> ~P & ~Q   2, deMorgan's law
4.  ~R -> ~Q & ~P   3, commutation   
5.  ~R -> ~Q        4, simplification

Edwin</pre>