Write the definition of a class Telephone. The class has no constructors,
one instance variable of type String called number,
and two static variables. One is of type int called quantity;
the other is of type double called total. Besides that,
the class has one static method makeFullNumber. The method accepts two arguments,
a String containing a telephone number and an int containing
an area code. The method concatenates the two arguments in the following manner: First comes the area code,
then a dash, then the telephone number. The method returns the resultant string.