A Venn diagram captioned: "In a survey of 250 European travelers, 93 have traveled to Africa, 155 have traveled to Asia, and 70 have traveled to both of these continents, as illustrated in the Venn ...

In set notation this is B = {1, 4, 9}. 30 people answered a survey about whether they have a dog or a cat. The Venn diagram shows the information from the survey. 13 people have got a dog.