conversations.from: human
conversations.value: There are 235 books in a library. On Tuesday, 227 books are taken out. On Thursday, 56 books are brought back and 35 books are taken out again on Friday. How many books are there now?
conversations.from: assistant
conversations.value: On Tuesday, 227 books were taken, so there are 235 - 227= 8 books left.
  56 books were brought back on Thursday, so there are 8 + 56 = 64 books in the library.
  Finally, 35 books are taken out on Friday, leaving 64 - 35 = 29 books available.