A and B work together to process 3600 machine parts in 4 hours. It is known that A can process 1900 in 5 hours. How many parts does B process per hour?
甲、乙两人4小时共同加工3600个机器零件，已知甲5小时可以加工1900，乙每小时加工多少个？
<gadget id="calculator">3_600 / 4</gadget>
<output>900</output>

<gadget id="calculator">1_900 / 5</gadget>
<output>380</output>

<gadget id="calculator">900 - 380</gadget>
<output>520</output>

<result>520</result>