The ratio of the tonnage of a pile of sand removed to the total tonnage is (3/7), and the rest is 2.1 tons more than the amount removed. How many tons is this pile of sand?
一堆沙运走的吨数与总吨数的比是(3/7)，剩下的比运走的多2.1吨，这堆沙有多少吨？
<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">2.1 / (1/7)</gadget>
<output>14.7</output>

<result>14.7</result>