Answer
See the diagram at the end of the explanation
Explanation
Given that the total number of surveyed people is 30 and 2 people don't like chocolate or vanilla ice creams, then 28 (= 30 - 2) people like at least one of these flavors.
Considering only the people who at least like one of the flavors, the next Venn diagram can be drawn:
where:
Combining the first and second equations, we get:
Combining the first and third equations, we get:
Substituting these results into the first equation:
Now, with these results we can draw the Venn diagram as follows (where the "2" outside the circles indicates the number of people who don't like chocolate or vanilla):