Sound travels 1.7 kilometers in air in 5 seconds. According to this calculation, how many seconds does it take to travel 10.2 kilometers? (Solution by proportional method)
声音在空气中5秒传1.7千米．照这样计算，传10.2千米，需要多少秒？(用比例方法解)
<gadget id="calculator">1.7 / 5</gadget>
<output>0.34</output>

<gadget id="calculator">10.2 / 0.34</gadget>
<output>30</output>

<result>30</result>