Class A has 42 students and Class B has 48 students. It is known that in a certain mathematics test, the papers are graded according to the percentage system. The results of the grades are that the total grades of mathematics in each class are the same, and the average grades of each class are all integers, and the average grades are all higher than 80 points. Then the average grade of Class A is higher than How tall is Class B?
甲班有42名学生，乙班有48名学生．已知在某次数学考试中按百分制评卷，评卷的结果各班的数学总成绩相同，各班的平均成绩都是整数，并且平均成绩都高于80分，那么甲班的平均成绩比乙班高多少．
<gadget id="calculator">12 * 8</gadget>
<output>96</output>

<gadget id="calculator">12 * 7</gadget>
<output>84</output>

<gadget id="calculator">96 - 84</gadget>
<output>12</output>

<result>12</result>