In an exam, the average scores of the three classes A, B, and C are 81, 97, and 91. It is known that the average score of the three classes is 92 points, and the average score of the two classes A and B is 93 points. So what is the average score of Classes A and C?
在一次考试中，甲，乙，丙三个班的平均成绩为81分，97分，91分．已知三个班平均分为92分，甲，乙两班平均成绩为93分．那么甲，丙两班平均成绩为多少？
<gadget id="calculator">91 - 81</gadget>
<output>10</output>

<gadget id="calculator">10 * 4</gadget>
<output>40</output>

<gadget id="calculator">1 + 4</gadget>
<output>5</output>

<gadget id="calculator">40 / 5</gadget>
<output>8</output>

<gadget id="calculator">81 + 8</gadget>
<output>89</output>

<result>89</result>