please include explanation for each line to fully understand. It also requires it to be done in 3 files.

Create a class named college Course that includes data fields that hold the department (CMPS), the course number (1302), the credit hours (3), and the fee for the course ($360). All of the fields are required as arguments to the constructor, except the fee, which is calculated at $120 per credit hour. Include a display () method that displays the course data. Create a subclass (child class) named Labcourse that adds $50 to the course fee for lab material. Override the parent display () method to indicate that the course is a lab course and to display the updated course fee. Write an application name Usecourse that prompts the user for course information. If the user enters a class in any of the following departments (BIOL, CHEM, CMPS, PHYS), create a Labcourse; otherwise create a Collegecourse. Then display the course information