However, based on their portrayals and behaviors, it's generally assumed that Fred, Daphne, Velma, and Shaggy are all college-aged or young adults.
This is supported by:
* Their roles: They are often depicted as students or recent graduates, traveling around and solving mysteries.
* Their personalities: While Fred takes on a leadership role, the others are still quite immature and prone to fear and silliness, typical of young adults.
It's important to note that this is just an inference based on the show's content. The creators have never confirmed their exact ages.