There are several piles of Go pieces, each pile has the same number of pieces, and each pile of black stones accounts for 72%. If half of the pieces are removed from a certain pile, and all of them are black, then black will account for 68% of all the pieces. How many piles of Go pieces are there?
有若干堆围棋子，每堆棋子数一样多，且每堆黑子都占72%．如果从某一堆中拿走一半棋子，且拿走的都是黑子，那么在所有棋子中，黑子将占68%．围棋子共有多少堆？
<gadget id="calculator">72 / 100</gadget>
<output>18/25 = around 0.72</output>

<gadget id="calculator">50 * (18/25)</gadget>
<output>36</output>

<gadget id="calculator">100 * (18/25)</gadget>
<output>72</output>

<gadget id="calculator">72 - 68</gadget>
<output>4</output>

<gadget id="calculator">36 / 4</gadget>
<output>9</output>

<result>9</result>