test_class.rb

class Fraction
  @numerator, @denominator = 0,0
  def initialize(n = 0,d = 0)
    @numerator, @denominator = n, d
  end
  def read
    @numerator, @denominator = gets.chomp, gets.chomp
  end
  def write
    puts "#{@numerator} / #{@denominator}"
  end
  def set(n = 0,d = 0)
    @numerator, @denominator = n, d
  end
end