The engineering team has built a road, which has already been built for 2.4 kilometers, which is exactly 1.6 times the remaining length. How many kilometers is this road?
工程队修一条路，已经修了2.4千米，正好是余下的1.6倍，这条路长多少千米？
<gadget id="calculator">2.4 / 1.6</gadget>
<output>1.5</output>

<gadget id="calculator">1.5 + 2.4</gadget>
<output>3.9</output>

<result>3.9</result>