There are two piles of sand, the second pile is (5/6) of the first pile, the second pile is (7/12) tons lighter than the first pile, how many tons is the first pile?
有两堆沙子，第二堆是第一堆的(5/6)，第二堆比第一堆轻(7/12)吨，第一堆多少吨？
<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">1 - (5/6)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(7/12) / (1/6)</gadget>
<output>7/2 = around 3.5</output>

<result>7/2 = around 3.5</result>