A road with a length of 2,400 meters has been repaired by 40% in the first 4 days. How many days will it take to complete the road at this speed? (Two ways to solve, one of which uses proportion)
一条长2400米的公路，前4天修了40%，照这样的速度修完这条公路共需多少天？(两种方法解答，其中一种用比例)
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / 4</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">2_400 * (1/10)</gadget>
<output>240</output>

<gadget id="calculator">2_400 / 240</gadget>
<output>10</output>

<result>10</result>