A and B process a batch of parts at the same time, and A's task is B's (2/3). A processes 60 per hour, and B processes 80 per hour. When A completes the task, B has 120 left. How many parts are there in this batch?
甲、乙两人同时加工一批零件，甲的任务是乙的(2/3)．甲每小时加工60个，乙每小时加工80个，当甲完成任务时，乙还剩120个．这批零件共有多少个？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">120 * (2/3)</gadget>
<output>80</output>

<gadget id="calculator">80 * (2/3)</gadget>
<output>160/3 = around 53.333333</output>

<gadget id="calculator">60 - (160/3)</gadget>
<output>20/3 = around 6.666667</output>

<gadget id="calculator">80 / (20/3)</gadget>
<output>12</output>

<gadget id="calculator">60 * 12</gadget>
<output>720</output>

<gadget id="calculator">80 * 12</gadget>
<output>960</output>

<gadget id="calculator">720 + 960 + 120</gadget>
<output>1_800</output>

<result>1_800</result>