conversations.from: human
conversations.value: A new edition Geometry book has 450 pages which are 230 pages less than twice as many pages as the old edition. How many pages did the old edition Geometry book have?
  Work out the solution step by step.
conversations.from: assistant
conversations.value: Let x be the number of pages of the old edition Geometry book
  The new edition Geometry book has 2x - 230 = 450 pages
  2x = 450 + 230
  2x = 680
  x = 340 pages