Pet Detective

A veterinarian surveys 26 of his patrons.   He discovers that 14 have dogs, 10 have cats, and 5 have fish.   Four have dogs and cats, 3 have dogs and fish, and one has a cat and fish.   If no one has all three kinds of pets, how many patrons have none of these pets?

Adapted from Oswego City School District Regents Exam Prep Center

Related InterMath investigation:
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