A truck traveled from Luliang to Kunming at a speed of 36 kilometers per hour, and it took 5 hours to arrive in Kunming. Returning to time, the empty car travels 45 kilometers per hour. How many hours does it take for this truck to return to Luliang from Kunming?
一辆货车从陆良往返昆明，去时重车的速度是每小时36千米，行了5小时到达昆明．返回时空车每小时行45千米．这辆货车从昆明返回陆良需多少个小时？
<gadget id="calculator">5 / 45</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">36 * (1/9)</gadget>
<output>4</output>

<result>4</result>