question: Gerald and Julia divided $100 in the ratio 3:2. If Gerald spent $10 on a book, how much money did he have left?
answer: The $100 was divided into 3 + 2 = <<3+2=5>>5 parts.
  So each part is $100/5 = $<<100/5=20>>20.
  So Gerald received $20 x 3 = $<<20*3=60>>60.
  Gerald bought a book at $<<10=10>>10.
  Therefore, Gerald was left with $60 - $10 = $<<60-10=50>>50.
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