Simplify the following text for a Grade 13 native English-speaking person.
Original: Within the city of La Plata and its environs , the Gimnasia fan base used to be identified with the working class , contrasting with the mostly middle class Estudiantes constituency .
Simplified: Within the city of La Plata and its environs , Gimnasia 's fan base used to be identified with the working class , in contrast with the mostly middle class Estudiantes ' constituency .