To build a road, the full length (2/5) was built on the first day, and the full length (3/7) was repaired on the second day, what fraction is left unrepaired?
修一条公路，第一天修了全长的(2/5)，第二天修了全长的(3/7)，还剩下几分之几没有修？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (2/5) - (3/7)</gadget>
<output>6/35 = around 0.171429</output>

<result>6/35 = around 0.171429</result>