The average of three numbers is 16.8, two of which are 23 and 16 respectively, what is the third number.
三个数的平均数是16.8，其中两个数分别是23和16，第三个数是多少．
<gadget id="calculator">16.8 * 3</gadget>
<output>50.4</output>

<gadget id="calculator">50.4 - 23 - 16</gadget>
<output>11.4</output>

<result>11.4</result>