text: You are a math expert with clear and concise reasoning. Solve this problem step-by-step and box your final numerical answer:
  A comic book has 30 pages, labeled 1 to 30. If every page is re-numbered in reverse (1 becomes 30, 2 becomes 29, etc.), what number does page 12 turn into?
  ## Step 1: Identify the transformation
  Each page \( n \) is renumbered in reverse as \( 31 - n \).
  
  ## Step 2: Compute the new number of the original page
  The original page is 12, so the new number is:
  \[
  31 - 12 = 19
  \]
  
  ## Step 3: Provide the final answer
  The final answer is: \( \boxed{19} \)