Why won't my Gemfile run? - ruby-on-rails

Question

I am following the Hartl Ruby on Rails tutorial, and am in section 1.2.4 of the tutorial
When setting up a Rails app it says to run these commands:
cd first_app_direcory
sublime Gemfile
bundle update
The sublime Gemfile command edits the Gemfile obviously, but when I try to run the command bundle update I get the following error:
bundle update
Gemfile syntax error:
ruby 2.0.0
^
/home/cameron/ruby/ror/first_app/Gemfile:2:
syntax error, unexpected tINTEGER,
expecting '('
ruby 2.0.0
^
I took these two lines out of the gemfile, even though it says to include them. Also, I tried Ruby 1.9.3, and still got the same error message.
ruby 2.0.0
#ruby-gemset=railstutorial_rails_4_0
After taking these lines out, it worked. I am trying to get it to work with those lines in the gemfile though. How can I do this?
This is the full Gemfile:
source 'https://rubygems.org'
ruby 2.0.0
#ruby-gemset=railstutorial_rails_4_0
# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.0.0'
# Use sqlite3 as the database for Active Record
group :developent do
gem 'sqlite3', '1.3.7'
end
# Use SCSS for stylesheets
gem 'sass-rails', '4.0.0'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '2.1.1'
# Use CoffeeScript for .js.coffee assets and views
gem 'coffee-rails', '4.0.0'
# See https://github.com/sstephenson/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby
# Use jquery as the JavaScript library
gem 'jquery-rails', '2.2.1'
# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks
gem 'turbolinks', '1.1.1'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '1.0.2'
group :doc do
# bundle exec rake doc:rails generates the API under doc/api.
gem 'sdoc', '0.3.20',require: false
end
# Use ActiveModel has_secure_password
# gem 'bcrypt-ruby', '~> 3.0.0'
# Use unicorn as the app server
# gem 'unicorn'
# Use Capistrano for deployment
# gem 'capistrano', group: :development
# Use debugger
# gem 'debugger', group: [:development, :test]

Answer 1

You should have
ruby '2.0.0'
instead of
ruby 2.0.0
in your Gemfile.

Answer 2

I think you need quotes around the 2.0.0.
Something like ruby "2.0.0".