def conversion_chart(from_units, to_units, values)
  puts "#{from_units}\t#{to_units}"
  left_line = right_line = ""
  from_units.length.times { left_line += '-' }
  to_units.length.times { right_line += '-' }
  puts "#{left_line}\t#{right_line}"
  for val in values
    converted = yield val
    puts "#{val}\t#{converted}"
  end
  puts
end

celsius_temps = [0,10,20,30,40,50,60,70,80,90,100]
conversion_chart("C", "F", celsius_temps) {|cel| cel * 9 / 5 + 32}

fahrenheit_temps = [0,10,20,30,40,50,60,70,80,90,100,110,120,130,140,150,160,170,180,190,200 ]
conversion_chart("Fahr.", "Celsius", fahrenheit_temps) {|fahr| (fahr-32) * 5 / 9 }


conversion_chart("Km", "Miles", (1..10)) do |km|
  mile = 0.621371 * km
end