Build a road with a total length of 120 kilometers. 15 kilometers were repaired in 3 days after starting work. According to this calculation, how many days will it take to complete the road?
修一条公路，总长120千米．开工3天修了15千米．照这样计算，修完这条公路还要多少天？
<gadget id="calculator">120 - 15</gadget>
<output>105</output>

<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<gadget id="calculator">105 / 5</gadget>
<output>21</output>

<result>21</result>