There are three piles of sand, the first pile has (7/2) tons, which is (7/9) of the second pile, the third pile is (1/5) more than the second pile, how many tons is there in the second pile?
有三堆沙子，第一堆有(7/2)吨，是第二堆的(7/9)，第三堆比第二堆多(1/5)，第二堆有多少吨？
<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">(7/2) / (7/9)</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>