The total length of a road is 12 kilometers, and 1.5 kilometers were repaired 3 days before the start of construction. According to this calculation, how many days will it take to complete the road?
修一条公路总长12千米，开工前3天修了1.5千米，照这样计算，修完这条路还需多少天？
<gadget id="calculator">12 - 1.5</gadget>
<output>10.5</output>

<gadget id="calculator">1.5 / 3</gadget>
<output>0.5</output>

<gadget id="calculator">10.5 / 0.5</gadget>
<output>21</output>

<result>21</result>