To build a road, it is planned to build 0.3 kilometers per day, and it will be completed in 20 days. As a result, 1.8 kilometers were repaired in 9 days. According to this calculation, how many days will it take to complete the road? (Answer with proportional knowledge)
修一条公路，计划每天修0.3千米，20天修完．结果开工9天修了1.8千米，照这样计算，修完这条公路共需要多少天？(用正比例的知识解答)
<gadget id="calculator">1.8 / 9</gadget>
<output>0.2</output>

<gadget id="calculator">20 / 0.2</gadget>
<output>100</output>

<gadget id="calculator">0.3 * 100</gadget>
<output>30</output>

<result>30</result>