Column formula calculation: (3/7) of a certain number is (2/5) of 6, find this number.
列式计算：某数的(3/7)是6的(2/5)，求这个数．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(2/5) / (3/7)</gadget>
<output>14/15 = around 0.933333</output>

<gadget id="calculator">6 * (14/15)</gadget>
<output>28/5 = around 5.6</output>

<result>28/5 = around 5.6</result>