conversations.from: human
conversations.value: Sue and her sister buy a $2,100 car.  They agree to split the cost based on the percentage of days use.  Sue's sister will drive the car 4 days a week and Sue will get the rest of the days.  How much does Sue have to pay?
  Find the solution.
conversations.from: assistant
conversations.value: Sue will drive 7-4=3 days a week
  So she will pay 2100*3/7=$900