The road construction team repaired a canal, and built (2/5) kilometers in the first week, and (11/35) kilometers in the second week, leaving just the full length (2/7). What is the total length of this canal in kilometers?
修路队修一条水渠，第一周修了(2/5)千米，第二周修了(11/35)千米，正好剩下全长的(2/7)．求这条水渠全长多少千米？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">11 / 35</gadget>
<output>11/35 = around 0.314286</output>

<gadget id="calculator">(2/5) + (11/35)</gadget>
<output>5/7 = around 0.714286</output>

<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">(5/7) / (5/7)</gadget>
<output>1</output>

<result>1</result>