conversations.from: human
conversations.value: A pencil costs $0.5 each and a folder costs $0.9 each. An office needs two dozen pencils and 20 pieces of folders. How much does it cost to buy the office supplies?
conversations.from: assistant
conversations.value: Two dozens of pencils are equal to 2 x 12 = 24 pencils.
  So the total cost of pencils is $0.5 x 24 = $12.
  The total cost of folders is $0.9 x 20 = $18.
  Thus, the cost to buy the office supplies is $12 + $18 = $30.