The manual group has to do 80 small flags. Already done (2/5), how many sides are left unfinished?
手工组要做80面小旗．已经做了(2/5)，还有多少面没做完？
<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">80 * (3/5)</gadget>
<output>48</output>

<result>48</result>