Three piles of go pieces have the same number, the first pile of black stones has the same number of white stones as the second pile, the third pile of black stones accounts for 2/5 of all black stones, how many white stones are mixed together.
三堆围棋子，数目一样多，第一堆黑子与第二堆白子一样多，第三堆黑子占全部黑子的(2/5)，混合在一起白子占全部多少．
<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<result>4/9 = around 0.444444</result>