The master and apprentice make 60 parts together. Half an hour later, the two left 20 parts unfinished. How many more minutes will pass before the two can complete the task.
师傅和徒弟一起做60个零件．半小时后两人还剩20个零件没完成．再经过多少分钟，两人才能完成任务．
<gadget id="calculator">60 - 20</gadget>
<output>40</output>

<gadget id="calculator">40 / 30</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">20 / (4/3)</gadget>
<output>15</output>

<result>15</result>