To build a concrete road (4/5) kilometers long, how many days will it take to build (1/4) of this road every day?
要修一条长(4/5)千米长的水泥路，每天修这条路的(1/4)，共用多少天修完．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / (1/4)</gadget>
<output>4</output>

<result>4</result>