The new fluorescent tube consumes (2/7) kilowatt-hours of electricity for 3 hours, how many kilowatt-hours of electricity is used per hour on average?
新型日光灯管3小时用电(2/7)千瓦时，平均每小时用电多少千瓦时？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(2/7) / 3</gadget>
<output>2/21 = around 0.095238</output>

<result>2/21 = around 0.095238</result>