To build a road, the full length (1/7) was repaired on the first day, and the full length (2/7) was repaired on the second day. How much was the total length repaired in two days?
修一条路，第一天修了全长的(1/7)，第二天修了全长的(2/7)，两天一共修了全长的多少
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(1/7) + (2/7)</gadget>
<output>3/7 = around 0.428571</output>

<result>3/7 = around 0.428571</result>