In the composition of air, oxygen accounts for about 20%, and what percentage of other substances account for the air composition?
空气的成分中，氧气约占20%，其他物质约占空气成分的百分之几？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>