There are three piles of black and white pieces with the same number. The number of black pieces in the first pile is the same as that of the white pieces in the second pile. The number of white pieces in the third pile is twice the number of black pieces. Find the proportion of black pieces in the third pile The percentage of all black pieces.
有黑白混合但数量相同的三堆棋子，第一堆的黑棋子和第二堆的白棋子数量相同，第三堆白棋子数是黑棋子数的2倍，求第三堆中的黑棋子占全部黑棋子的百分比．
<gadget id="calculator">1 * 2</gadget>
<output>2</output>

<gadget id="calculator">1 + 1 + 2</gadget>
<output>4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>