question: Ben bought a car for $20000 in 2007. The price of the car depreciates at a constant rate of 21% per year. Find the price of the car in the year 2010.
answer: The price of the car depreciates of 20000 * 21% = $<<20000*21*.01=4200>>4200 per year.
  Ben had the car for 2010 - 2007 = <<2010-2007=3>>3 years.
  The price of the car depreciates 4200 * 3 = $<<4200*3=12600>>12600 from 2007 to 2010.
  So the price of the car in the year 2010 is $20000 - $12600 = $<<20000-12600=7400>>7400.
  #### 7400