The number of goals scored by the four football teams A, B, C, and D in the National League A is: 9, 9, x, 7. If the mode of this set of data is exactly equal to the mean, what is the median of this set of data
甲乙丙丁四支足球队在全国甲级联赛中进球的数目分别是：9，9，x，7，若这组数据的众数与平均数恰好相等，则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>