Simplify the following text for a Grade 10 native English-speaking person.
Original: Miami-Dade County ( formerly known as Dade County and many times referred to as simply Miami or Dade ) is a county located in the southeastern part of the state of Florida .
Simplified: Miami-Dade County ( often referred to as simply Miami-Dade , Dade County , or Dade ) is a county located in the southeastern part of the state of Florida .