conversations.from: human
conversations.value: Mark is looking to buy a total of 12 pieces of fruit at the store. He has already chosen 3 apples. He has also selected a bunch of bananas containing 4 bananas. How many oranges does he need to pick out to have 12 total pieces of fruit?
  Give me a clear explanation.
conversations.from: assistant
conversations.value: He has 3 apples and 4 bananas, so he has 3 + 4 = 7 pieces of fruit.
  He needs to buy 12 fruit - 7 fruit = 5 oranges.