One day, 6 classmates went to play table tennis from 10:00 am to 11:20 am. If they have been playing doubles during this period of time (that is, 4 players must play at the same time), how many minutes is the average playing time of one person?
某天，6个同学去打乒乓球，从上午10：00一直到上午11：20．若这段时间内，他们一直玩双打(即须4人同时上场)，则平均一个人的上场时间为多少分钟．
<gadget id="calculator">4 * 80</gadget>
<output>320</output>

<gadget id="calculator">320 / 5</gadget>
<output>64</output>

<result>64</result>