The road construction team builds a road with a length of 4.2 kilometers. What has been repaired is not repaired (2/5). How many kilometers are left to be repaired?
修路队修一条长4.2千米的公路，已修的是未修的(2/5)，还剩多少千米没有修？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 + (2/5)</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">4.2 / (7/5)</gadget>
<output>3</output>

<result>3</result>