There are 51 students in class A and 49 students in class B. The average score of all students in a certain test is 81 points. The average score of class B is 7 points higher than that of class A. So what is the average score of class B?
甲班51人，乙班49人，某次考试全体同学的平均成绩是81分，乙班的平均成绩要比甲班成绩高7分，那么乙班的平均成绩是多少分？
<gadget id="calculator">51 + 49</gadget>
<output>100</output>

<gadget id="calculator">100 * 81</gadget>
<output>8_100</output>

<gadget id="calculator">49 * 7</gadget>
<output>343</output>

<gadget id="calculator">8_100 - 343</gadget>
<output>7_757</output>

<gadget id="calculator">7_757 / 100</gadget>
<output>7_757/100 = around 77.57</output>

<gadget id="calculator">(7_757/100) + 7</gadget>
<output>8_457/100 = around 84.57</output>

<result>8_457/100 = around 84.57</result>