conversations.from: human
conversations.value: I need help with this problem:
  A water tank is filled with 120 liters of water. Celine used 90 liters of water from the tank to water her small garden. She was then able to collect rainwater that is twice as much as what was left. How many liters of water are in the tank now?
conversations.from: assistant
conversations.value: After watering Celine's garden, 120 - 90 = 30 liters of water were left in the tank.
  Celine was able to collect 30 x 2 = 60 liters of rainwater.
  Thus, there are 30 + 60 = 90 liters of water in the tank.