Divide 3 tons into 7 parts on average, each part is 3 tons ((())/(())), how many tons does each part weigh.
把3吨平均分成7份，每份是3吨的((())/(()))，每份重多少吨．
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 / (1/7) / 1</gadget>
<output>7</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<result>3/7 = around 0.428571</result>