The two masters and apprentices in the assembly workshop process the same number of parts. When the master completed half, the apprentice completed 120. When the master completes the task, the apprentice completes four-fifths. How many parts are there in this batch?
装配车间的师徒两人加工同样多的零件．当师傅完成了一半时，徒弟完成了120个．当师傅完成了任务时，徒弟完成了五分之四．这批零件共有多少个？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">2 / (4/5)</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">120 * (5/2) * 2</gadget>
<output>600</output>

<result>600</result>