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That's the probability that you chose one of these 12 cards:
           3♥   4♥   5♥  
           3♦   4♦   5♦
           3♠   4♠   5♠ 
           3♣   4♣   5♣   
out of these 52 cards:
A♥   2♥   3♥   4♥   5♥   6♥   7♥   8♥  9♥  10♥  J♥  Q♥  K♥ 
A♦   2♦   3♦   4♦   5♦   6♦   7♦   8♦  9♦  10♦  J♦  Q♦  K♦
A♠   2♠   3♠   4♠   5♠   6♠   7♠   8♠  9♠  10♠  J♠  Q♠  K♠  
A♣   2♣   3♣   4♣   5♣   6♣   7♣   8♣  9♣  10♣  J♣  Q♣  K♣ 
That's a probability of 12 out of 52, and "out of" means "over", so
that's a probability of 12 over 52 or  and that fraction
reduces to 3/13.
Edwin
 and that fraction
reduces to 3/13.
Edwin