The sum of the three numbers A, B and C is 25.2, the average of A and C is 8.2, the average of B and C is 8, find the number of C.
甲、乙、丙三个数的和是25.2，甲、丙的平均数是8.2，乙、丙的平均数是8，求丙数．
<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<gadget id="calculator">25.2 - 16</gadget>
<output>9.2</output>

<gadget id="calculator">8.2 * 2</gadget>
<output>16.4</output>

<gadget id="calculator">25.2 - 16.4</gadget>
<output>8.8</output>

<gadget id="calculator">25.2 - 9.2 - 8.8</gadget>
<output>7.2</output>

<result>7.2</result>