Well, here is my submission.. I truly was stuck with this so I just done 
the most basic stuff, I will have a look through the other submissions a 
bit later to see how others done it..

#!/usr/bin/ruby -w

argv = Array.new
if ARGV.empty?
  puts "#{$0} <Postfix equation>"
else
  ARGV.each do |a|
    if ['+', '-', '/', '*'].include?(a)
      last = argv.pop
      first = argv.pop
      argv << "(#{first} #{a} #{last})"
    else
      argv << a
    end
  end
  puts argv
end


I will try and mod the code to remove some parenthesis.

Regards,
Lee
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