The road builders repair a road. They repaired it in the first month (2/7), and in the second month (3/7). How much more will be repaired in the third month to finish all the repairs?
筑路工人修一条路，第一个月修了(2/7)，第二个月修了(3/7)，第三个月还要修多少才能全都修完？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

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

<gadget id="calculator">1 - (2/7) - (3/7)</gadget>
<output>2/7 = around 0.285714</output>

<result>2/7 = around 0.285714</result>