To build a 15km long road, 1.8km was built in the first 3 days. According to this calculation, how many days will it take to complete the road?
修一条长15km的公路，前3天修了1.8km．照这样计算，修完这条路还要多少天？
<gadget id="calculator">15 - 1.8</gadget>
<output>13.2</output>

<gadget id="calculator">1.8 / 3</gadget>
<output>0.6</output>

<gadget id="calculator">13.2 / 0.6</gadget>
<output>22</output>

<result>22</result>