设一个班有4个学生，每个学生有学号，以及数学、物理、英语、语文、体育5门课的成绩信息。分别编写3个函数以实现以下3个要求。

（1）求数学的平均成绩。

（2）对于有两门以上课程不及格的学生，输出他们的学号、各门课成绩及平均成绩。

（3）输出成绩优良的学生（平均成绩在85分以上或全部成绩都在80分以上）的学号、各门成绩和平均成绩。

-There are four students in a class, each student has a student number, as well as mathematics, physics, English, Chinese, sports information 5 classes. Write the three functions respectively in order to achieve the following three requirements.

(1) the mathematical average grades.

(2) failed to have two or more classes of students, the output of their student id, each course result and grade point average.

(3) the output result good student (grade point average in more than 85 points or all of the scores are more than 80 points) of the student number, each grades and gpa.