I am using unity 4.7 as 4.x is required for the first half of my online course.
The error is correct, store and shopping are defined as enum values of the States enumeration. They are not methods. On lines 37 and 44 just remove the parentheses.
Sorry, accidentally deleted part of the details section. Error is that is says I can not use a value as a method. It is exactly as my teacher wrote it though.