document.write( "Question 474140: Proof for:
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Algebra.Com's Answer #325711 by Edwin McCravy(20059)\"\" \"About 
You can put this solution on YOUR website!
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document.write( " P -> Q Therefore ~Q -> ~P\r\n" );
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document.write( "P  Q  (P -> Q)  ~Q  ~P  (~Q->~P) \r\n" );
document.write( "T  T     T       F   F      T\r\n" );
document.write( "T  F     F       T   F      F\r\n" );
document.write( "F  T     T       F   T      T\r\n" );
document.write( "F  F     T       T   T      T\r\n" );
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document.write( "They have the same truth table TFTT\r\n" );
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document.write( "Edwin
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