Li Ming loaded 3.6 tons of cargo from City A to City B, traveling an average of 60 kilometers per hour and arriving in 8 hours. He received a call from home at 8:00 the next morning and had to rush back at 2:00 in the afternoon. If Li Ming returned by the same route, he must ensure at least an average speed?
李明从甲城装3.6吨货物到乙城，平均每小时行60千米，8小时到达．第二天早上8点接到家里电话需下午两点赶回，李明如果原路返回，必须保证至少平均速度为多少？
<gadget id="calculator">8 / 6</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">60 * (4/3)</gadget>
<output>80</output>

<result>80</result>