conversations.from: human
conversations.value: A water tower that serves four neighborhoods around it holds 1200 barrels of water and is filled to the top each week. If one neighborhood uses 150 barrels of water in a week, the second neighborhood uses twice as many barrels of water as the first neighborhood in a week, and the third neighborhood uses one hundred more barrels of water than the second neighborhood in a week, how many barrels are left for the fourth neighborhood?
  Give me a detailed solution.
conversations.from: assistant
conversations.value: The second neighborhood uses 150 * 2 = 300 barrels of water.
  The third neighborhood uses 300 + 100 = 400 barrels of water.
  The first, second, and third neighborhoods together use 150 + 300 + 400 = 850 barrels of water.
  Thus, the fourth neighborhood has 1200 - 850 = 350 barrels of water left for it to use.