text: You are a math expert with clear and concise reasoning. Solve this problem step-by-step and box your final numerical answer:
  You have a thesis with 35 pages, originally labeled 1 to 35. It's renumbered in reverse (1 becomes 35, 2 becomes 34, and so on). What does page 20 become?
  ## Step 1: Identify the transformation
  Each page \( n \) is renumbered in reverse as \( 36 - n \).
  
  ## Step 2: Compute the new number of the original page
  The original page is 20, so the new number is:
  \[
  36 - 20 = 16
  \]
  
  ## Step 3: Provide the final answer
  The final answer is: \( \boxed{16} \)