conversations.from: human
conversations.value: Two months ago, Wilson had a total of $150 in his bank account. Then last month, he deposited $17. A few days after, he made a withdrawal. This month, he deposited $21 so he has $16 more than what is in his account two months ago. How much did Wilson withdraw last month?
  Give me a clear explanation.
conversations.from: assistant
conversations.value: Wilson had $150 + $17= $167 two months ago before making a withdrawal.
  His money in his account now is $150 + $16 = $166.
  Since he deposited $21 this month, this means there was $166 - $21 = $145 last month after making a withdrawal.
  Therefore, Wilson withdrew $167 - $145 = $22.