Two workers, A and B, work together to process a batch of parts. A processes 16 pieces per hour, and B processes 12 pieces per hour. The two workers start work at the same time, and the working hours are the same. When the task is completed, B processes 20 fewer parts than A. how many.
甲乙两个工人共同加工一批零件，甲每小时加工16个，乙每小时加工12个，两人同时开工，工作时间相同，到完成任务时，乙比甲少加工20个，这批零件一共多少个．
<gadget id="calculator">16 + 12</gadget>
<output>28</output>

<gadget id="calculator">16 - 12</gadget>
<output>4</output>

<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">28 * 5</gadget>
<output>140</output>

<result>140</result>