A set of data 3, 8, 5, 7, 12, the median of x is 6.5, then what is x.
一组数据3，8，5，7，12，x的中位数是6.5，那么x是多少．
<gadget id="calculator">6.5 * 2</gadget>
<output>13</output>

<gadget id="calculator">13 - 7</gadget>
<output>6</output>

<result>6</result>