truck pulls goods from Kunming to Chuxiong, travels 55 kilometers per hour, and arrives in 3 hours. Empty cars returned to Kunming from Chuxiong and traveled 66 kilometers per hour. How much less time did the truck take to return to Kunming?
一辆卡车从昆明拉货到楚雄，每小时行55千米，3小时到达．空车从楚雄返回昆明每小时行66千米．这辆卡车返回昆明时少用了多少时间？
<gadget id="calculator">3 / 66</gadget>
<output>1/22 = around 0.045455</output>

<gadget id="calculator">55 * (1/22)</gadget>
<output>5/2 = around 2.5</output>

<result>5/2 = around 2.5</result>