title: Passing a splat parameter from one method to another method
body: <p>I would like to create methods called 'add' and 'subtract' using splat parameter as below:</p>
  
  <pre><code>def add(*numbers)
    numbers.inject(0) { |sum, n| sum + n }
  end
  
  def subtract(*numbers)
    numbers[0] - add(numbers[1..-1])
  end
  </code></pre>
  
  <p>But it didn't work.
  What should I do to pass the splat parameter from one to another? (Especially for some specific range...)</p>
  
  <p>Thank you!</p>