conversations.from: human
conversations.value: James is putting together 4 tables.  Each table has 4 legs and each leg needs 2 screws.  He has 40 screws.  How many screws will he have left over?
conversations.from: assistant
conversations.value: Each table will take 4*2=8 screws
  So he needs 8*4=32 screws
  That means he will have 40-32=8 screws left over