Given a set of data 9, 9, X, 7, the mode of this set of data is exactly equal to the mean, then what is the median of this set of data
已知一组数据9、9、X、7，这组数据众数与平均数恰好相等，那么这组数据的中位数是多少
<gadget id="calculator">9 + 9</gadget>
<output>18</output>

<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<result>9</result>