60% of a road with a length of 210km has been built, how many kilometers are left to be repaired?
修一条长210km的公路，已经修了60%，还剩多少千米没修？
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">210 * (2/5)</gadget>
<output>84</output>

<result>84</result>