Answer:
Window.java
Main.java
Explanation:
Window.java
There is a Window class with two int type attributes, width and height (Line 1 - 3).
The constructor of this class will take two inputs, width and height and set these input to its attributes (Line 5 - 8). There are two methods getWidth and getHeight which will return the value of attributes width and height, respectively (Line 10 - 16).
The required new method getClientAreaHeight is defined in line 18 -20. This method will call the getHeight method to return the height value of the window (Line 19).
Main.java
We test the Window class by creating one Window instance and call the getClientAreaHeight method and print the return output (Line 1 -6).
We shall see 15 is printed.