Question 1207607
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At my office, 18 people own cats, 27 people own dogs, and 14 people own both cats and dogs.  
How many people own a cat or a dog?
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The number of people that own a cat or a dog is 

    18 + 27 - 14 = 31.     <U>ANSWER</U>


The general formula is

    N(own a cat or own a dog) = N(own a cat) + N(own a dog) - N(own a cat and a dog).
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Solved.