question: Jennie is helping at her mom's office. She has a pile of 60 letters needing stamps, and a pile of letters already stamped. She puts stamps on one-third of the letters needing stamps. If there are now 30 letters in the pile of already-stamped letters, how many were in that pile when Jennie began?
answer: She stamped 60/3=<<60/3=20>>20 letters.
  Then there were 30-20=<<30-20=10>>10 in the already-stamped pile to begin with.
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