Aunt Zhang runs a sporting goods store. Once, she bought a batch of balls at a price of 6 yuan each and planned to sell them at 8 yuan each. 10% off the sale, and when all the balls were sold, Aunt Zhang made a total profit of 216 yuan. Ask: How many balls did Aunt Zhang buy in total?
张阿姨经营着一个体育用品商店，一次，她购进了一批皮球，进价是每个6元，打算以每个8元的价格卖出，实际上她在原定卖价的基础上打九折卖出，当这批皮球全部卖出后，张阿姨共获利润216元，问：张阿姨买进的这批皮球一共有多少个？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">8 * (9/10)</gadget>
<output>36/5 = around 7.2</output>

<gadget id="calculator">(36/5) - 6</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">216 / (6/5)</gadget>
<output>180</output>

<result>180</result>