Uncle Wang set off from the county seat to Wangzhuang Township to deliver fertilizers. The speed of going is 42 km/h, and the speed of returning is 63 km/h. It took 2 hours. How many hours did it take to deliver the goods?
王叔叔从县城了出发去王庄乡送化肥．去的速度是42千米/时，回来的速度是63千米/时，用了2小时，送货去的时候用了几小时？
<gadget id="calculator">2 / 42</gadget>
<output>1/21 = around 0.047619</output>

<gadget id="calculator">63 * (1/21)</gadget>
<output>3</output>

<result>3</result>