There are 40 students in Class 5 ① and 45 students in Class 5 ②. In the mid-term exam, the average math scores of the two classes are the same. The total score of Class 5 ② is 393 points higher than that of Class 5 ①. What is the average score of these two classes in mathematics?
五①班有40人，五②班有45人，期中考试时两个班的数学平均分相同，五②班的总分比五①班多了393分．这两个班数学的平均分是多少分？
<gadget id="calculator">45 - 40</gadget>
<output>5</output>

<gadget id="calculator">393 / 5</gadget>
<output>393/5 = around 78.6</output>

<result>393/5 = around 78.6</result>