An engineering team wants to pave a road, and 2.8 kilometers have been paved in the first 20 days. According to this calculation, how many days will it take to pave the remaining 4.2 kilometers? (Solve with ratio)
某工程队要铺设一条公路，前20天已铺设了2.8千米，照这样计算，剩下的4.2千米，还要多少天才能铺完？(用比例解)
<gadget id="calculator">2.8 / 20</gadget>
<output>0.14</output>

<gadget id="calculator">4.2 / 0.14</gadget>
<output>30</output>

<result>30</result>