The electricity consumption in September is less than that in August (1/5), and the electricity consumption in September is equivalent to that in August.
九月份用电量比八月份少(1/5)，九月份的用电量相当与八月份的多少．
<gadget id="calculator">1 / 5</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>