3.  A file has lines with a student's name, the postal code for his state of
    residence, and his three SAT scores such as:

    Doe,John SD 800 640 710

    You will write a Perl script which takes the name of this input file
    plus the name of an output file on the command line.  The output file
    will list the postal codes and the AVERAGE total SAT score (such as
    the 2150 total for the line above) for that state.  Of course, the
    input file may have MANY people representing any given state.  Make
    the average given be an INTEGER average e.g., SD 1745.  

    The output file should be in DESCENDING ORDER OF AVERAGE.  Sorting
    will be discussed Wednesday but after Monday you will have most of
    what you need to finish this.  Note that the person's NAME is 
    irrelevant!!