Answer:
3 of the cities surveyed had only a professional sports team.
Step-by-step explanation:
We solve this question treating these as Venn sets.
I am going to say that:
Set A: professional sports team.
Set B: Symphony.
Set C: Children's museum.
We start building from the intersection of these three.
6 had all three activities.
This means that
10 had a symphony and a children's museum,
This means that:
That is, 4 have only the symphony and children's museum, while 6 have all three.
10 had a professional sports team and a children's museum
14 had a professional sports team and a symphony
21 had a professional sports team
This means that:
In which (A - B - C) represents the cities which had only a sports team. So
3 of the cities surveyed had only a professional sports team.