The average of the numbers A and B is 25, the average of the three numbers A, B and C is 24, what is the number of C?
甲、乙两数的平均数是25，甲、乙丙三数的平均数是24，丙数是多少．
<gadget id="calculator">24 * 3</gadget>
<output>72</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<gadget id="calculator">72 - 50</gadget>
<output>22</output>

<result>22</result>