conversations.from: human
conversations.value: The price of electricity went up by 25%.  John's old computer used 800 watts and his new computer uses 50% more.  If the old price of electricity was 12 cents per kilowatt-hour, how much does his computer cost, in dollars, to run for 50 hours?
conversations.from: assistant
conversations.value: His new computer uses 800*.5=400 watts more than his old computer
  So it users 800+400=1200 watts
  That is 1200/1000=1.2 kw
  Electricity cost 12*.25=3 cents more than it used to
  So it now cost 12+3=15 cents per kwh
  He used 1.2*50=60 kwh
  So he paid 15*60=900 cents per kwh
  So he paid 900/100=$9