Chapter 8, Problem 7E

Explanation of Solution

Adding mutator method in “TimeSpan” class:

//definition of "TimeSpan" class

public class TimeSpan

{

    //declare the required variables

    private int hours;

    private int minutes;

    //definition of "add" method

    public void add(TimeSpan span)

    {

        //calculate the hours

        hours += span.hours;

        //calculate the minutes

        minutes += span...