Build a highway (5/7) kilometers, A has repaired the full length (1/5), B has repaired the full length (1/4), and there is still the full length ((())/(())) build.
修一条公路(5/7)千米，甲修了全长的(1/5)，乙修了全长的(1/4)，还剩全长的((())/(()))没修．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/5) - (1/4)</gadget>
<output>11/20 = around 0.55</output>

<result>11/20 = around 0.55</result>