The road repair team repaired a 6-kilometer highway. The full length (3/7) was repaired in the first week, and the full length (4/9) was repaired in the second week. What fraction of the full length is left unrepaired?
修路队修一条6千米的公路，第一周修了全长的(3/7)，第二周修了全长的(4/9)，还剩下全长的几分之几没有修？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">1 - (3/7) - (4/9)</gadget>
<output>8/63 = around 0.126984</output>

<result>8/63 = around 0.126984</result>