The road repair team repaired a road, repaired the full length (1/7) in the first ten days, repaired the full length (1/8) in the middle ten days, and repaired as much in the second ten days as in the first ten days. What fraction of the full length is left unrepaired?
修路队修一条路，上旬修了全长的(1/7)，中旬修了全长的(1/8)，下旬修的和上旬修的同样多．还剩全长的几分之几没有修？
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 - (1/7) - (1/8) - (1/7)</gadget>
<output>33/56 = around 0.589286</output>

<result>33/56 = around 0.589286</result>