Build a road with a length of 9.7 kilometers. The first day repaired 1.35 kilometers, and the first day repaired 0.2 kilometers more than the second day. How many kilometers of roads are left unrepaired?
修一条长9.7千米的公路．第一天修了1.35千米，第一天比第二天多修0.2千米．还剩下多少千米的公路未修？
<gadget id="calculator">1.35 - 0.2</gadget>
<output>1.15</output>

<gadget id="calculator">9.7 - 1.35 - 1.15</gadget>
<output>7.2</output>

<result>7.2</result>