conversations.from: human
conversations.value: A bicycle shop owner adds 3 bikes to her stock every week. After 1 month, she had sold 18 bikes but still had 45 bikes in stock. How many bikes did she have originally?
conversations.from: assistant
conversations.value: There are approximately 4 weeks in a month.
  The shop owner added 3 bikes every week for 4 weeks for a total addition of 3*4 = 12 bikes
  The shop owner now has the original number of bikes + 12 bikes
  She sold 18 bikes within the same time frame
  She now has a total of 45 bikes which is: the original number of bikes + 12 - 18 = 45 bikes
  The original number of bikes = 45-12+18 = 51 bikes