conversations.from: human
conversations.value: Can you walk me through the solution of: James decides to start making his own coffee.  He buys a coffee machine for $200 and gets a $20 discount.  He figures it will cost him $3 a day to make his coffee.  He previously bought 2 coffees a day for $4 each.   How long until the machine pays for itself?
conversations.from: assistant
conversations.value: He bought the machine for $200-$20=$180
  He used to spend 4*2=$8 a day
  So he saves $8-$3=$5 a day
  So it will take him $180/$5=36 days to pay for itself