To build a 400-meter road, 320 meters have been built, and there is still much of the full length left.
修一条400米的马路，已修了320米，还剩下全长的多少没有修完．
<gadget id="calculator">400 - 320</gadget>
<output>80</output>

<gadget id="calculator">80 / 400</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>