question: James decides to buy birthday candles for his 2 sons.  One of them is 12 and the other is 4 years younger.  A pack of 5 candles costs $3.  How much does James spend on candles?
answer: His younger son is 12-4=<<12-4=8>>8 years old
  So he needs 12+8=<<12+8=20>>20 candles
  That means he needs 20/5=<<20/5=4>>4 packs of candles
  The total cost of those is 4*3=$<<4*3=12>>12
  #### 12