Build a road with a length of 19.7 kilometers. On the first day, we repaired 6.35 kilometers, and on the second day, we repaired 0.2 kilometers more than the first day. How many kilometers of roads are left unrepaired?
修一条长19.7千米的公路．第一天修了6.35千米，第二天比第一天多修0.2千米．还剩下多少千米的公路未修？
<gadget id="calculator">6.35 + 0.2</gadget>
<output>6.55</output>

<gadget id="calculator">19.7 - 6.35 - 6.55</gadget>
<output>6.8</output>

<result>6.8</result>