conversations.from: human
conversations.value: Find the answer to the math problem: John buys 1000 balloons.  Each balloon holds 10 liters of air.  If he buys 500-liter tanks of gas, how many tanks does he need to buy to fill all the balloons?
conversations.from: assistant
conversations.value: He needs 1000*10=10000 liters of gas
  So he needs 10000/500=20 tanks