Usually, the atmospheric phenomenon of low visibility when the humidity is greater than 90% is called fog, and when the humidity is less than 80%, it is called haze. So what is the humidity of fog and haze? How many
通常把在湿度大于90%的低能见度大气现象称之为雾，而湿度小于80%时称之为霾，那么雾霾的湿度是多少？多少
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">(4/5) - (9/10)</gadget>
<output>-1/10 = around -0.1</output>

<result>-1/10 = around -0.1</result>