conversations.from: human
conversations.value: After Andrea saved some money, she then spent the rest of her money on an $11 sweater and gave her brother $4. If she had $36 in the beginning, how much did Andrea save?
  Give me a detailed solution.
conversations.from: assistant
conversations.value: Andrea spent and gave her brother a total of $11 + $4 = $15.
  So, she saved $36 - $15 = $21.