A road has been built for 180 meters, and the rest is 30 meters shorter than the total length (2/5). How long is this road in meters?
一条路已修了180米，余下的比全长的(2/5)少30米，这条路长多少米．
<gadget id="calculator">180 - 30</gadget>
<output>150</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">150 / (3/5)</gadget>
<output>250</output>

<result>250</result>