conversations.from: human
conversations.value: I'm stuck on this math problem: Mel uses a 900-watt air conditioner for 8 hours a day. This means that each hour the AC uses 900 watts of energy. If he reduces the time he uses the air conditioner by 5 hours a day, how many kilowatts of electric energy will he save in 30 days?
  Can you help?
conversations.from: assistant
conversations.value: An air conditioner uses 900 x 8 = 7200 watts for 8 hours a day.
  An air conditioner uses 900 x 5 = 4500 watts for 5 hours a day.
  So, Mel saves 7200 - 4500 = 2700 watts per day.
  That is 2700/1000 = 2.7 kilowatts per day since 1 kilowatt is equal to 1000 watts.
  Hence, in 30 days he will have 2.7 x 30 = 81 kilowatts of electric energy saved.