There are two classes in the sixth grade in a certain school, and the average score in mathematics in the last semester was 85 points. It is known that there are 40 students in Class Six 1, with an average score of 87.1; there are 42 students in Class Six 2, what is the average score?
某校六年级有两个班，上学期级数学平均成绩是85分．已知六1班40人，平均成绩为87.1分；六2班有42人，平均成绩是多少分？
<gadget id="calculator">42 + 40</gadget>
<output>82</output>

<gadget id="calculator">85 * 82</gadget>
<output>6_970</output>

<gadget id="calculator">87.1 * 40</gadget>
<output>3_484</output>

<gadget id="calculator">6_970 - 3_484</gadget>
<output>3_486</output>

<gadget id="calculator">3_486 / 42</gadget>
<output>83</output>

<result>83</result>