question: Tom buys a bedroom set for $3000.  He sells his old bedroom for $1000 and uses that to pay for part of the bedroom set.  He then has to pay 10% a month for the bedroom set.  How much does he have to pay per month?
answer: He has to pay 3000-1000=$<<3000-1000=2000>>2000
  So he has to pay 2000*.1=$<<2000*.1=200>>200 per month
  #### 200