A and B work together to process 684 parts. After 18 days, A processes 25 parts per day, and how many parts does B process per day?
甲、乙两人合作加工684个零件，经过18天完成，甲每天加工25个，乙每天加工多少个？
<gadget id="calculator">684 / 18</gadget>
<output>38</output>

<gadget id="calculator">38 - 25</gadget>
<output>13</output>

<result>13</result>