To build a road with a length of 14Km, (2/7) of it has been repaired, how many Km are left?
修一条长14Km的路，已经修了它的(2/7)，还剩下多少Km．
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 - (2/7)</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">14 * (5/7)</gadget>
<output>10</output>

<result>10</result>