Question

A survey of 110 tourists was taken in St. Louis. The survey showed the following:

61 of the tourists plan to visit the Gateway Arch;
45 plan to visit the zoo;
9 plan to visit the Art Museum and the zoo, but not the Gateway Arch;
13 plan to visit the Art Museum and the Gateway Arch, but not the zoo;
18 plan to visit the Gateway Arch and the zoo, but not the Art Museum;
7 plan to visit the Art Museum, the zoo, and the Gateway Arch
16 plan to visit none of the three places.

How many plan to visit the Art Museum only?