There is a barrel of oil, after taking out (3/7), the remaining is 6 kg more than what was taken out, how many kilograms are taken out.
有一桶油，取出(3/7)后，剩下的比取出的多6千克，取出了多少千克．
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (3/7) - (3/7)</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">6 / (1/7)</gadget>
<output>42</output>

<result>42</result>