In October, due to the drop in temperature, the electricity consumption of the school dropped (2/7) compared to September, and the result was 210 kWh less. Do you know how much electricity the school used in September?
十月份由于气温下降，学校用电量比九月份下降了(2/7)，结果少用了210千瓦时，你知道九月份学校用电量是多少吗？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">210 / (2/7)</gadget>
<output>735</output>

<result>735</result>