If 45% of a bottle of water is poured out, how much is left?
一瓶水倒掉45%，还剩多少．
<gadget id="calculator">45 / 100</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">1 - (9/20)</gadget>
<output>11/20 = around 0.55</output>

<result>11/20 = around 0.55</result>