A road is 50 kilometers long, and it has been repaired for 4 days and the full length (3/5) is left. How many days will it take to finish the remaining road?
修一条路长50千米，已修4天还剩全长的(3/5)，这计算，修完剩下的路还要多少天？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">10 - 4</gadget>
<output>6</output>

<result>6</result>