The distance between A and B is 336 kilometers. A truck has traveled 168 kilometers from A to B, and it took 4 hours. According to this calculation, how many hours does it take to go from A to B?
A、B两地相距336千米，一辆货车从A地到B地已行驶了168千米，用了4小时，照这样计算，它从A地出发到B地需要多少小时？
<gadget id="calculator">168 / 4</gadget>
<output>42</output>

<gadget id="calculator">336 / 42</gadget>
<output>8</output>

<result>8</result>