To build a road with a length of 400 meters, 120 meters have been built, how many meters should be repaired to be the full length (3/5).
修一条长400米的路，已经修了120米，再修多少米恰好是全长的(3/5)．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">400 * (3/5)</gadget>
<output>240</output>

<gadget id="calculator">240 - 120</gadget>
<output>120</output>

<result>120</result>