and B work together to process a batch of parts, and the task can be completed in 8 hours. If A is processed alone, it will take 12 hours to complete. Now A and B have worked together for 2.4 hours, A is called out to do other work, and B continues to produce 420 parts to complete the task. How many parts does B process in total?
甲乙二人共同加工一批零件，8小时可完成任务．如果甲单独加工，便需要12小时完成．现在甲、乙二人共同生产了2.4小时后，甲被调出做其他工作，由乙继续生产了420个零件才完成任务．乙一共加工零件多少个．
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">2.4 * (1/8)</gadget>
<output>0.3</output>

<gadget id="calculator">1 - 0.3</gadget>
<output>0.7</output>

<gadget id="calculator">420 / 0.7</gadget>
<output>600</output>

<gadget id="calculator">50 * 2.4</gadget>
<output>120</output>

<gadget id="calculator">600 - 120</gadget>
<output>480</output>

<result>480</result>