The engineering team wanted to build a 20-kilometer road. They built 8.5 kilometers in the first week and 7.4 kilometers in the second week. How many kilometers are left to be repaired?
工程队要修一条长20千米的公路，第一周修了8.5千米，第二周修了7.4千米，还剩多少千米没有修？
<gadget id="calculator">20 - 8.5 - 7.4</gadget>
<output>4.1</output>

<result>4.1</result>