a.cpp

class StudentSpec {
public:
  int math;
  int english;
  StudentSpec  *next;
  StudentSpec(int english, int math, StudentSpec *next) {
    this->english = english;
    this->math = math;
    this->next = next;
  }

  void addList(StudentSpec *next) {
    this->next = next;
  }

  void removeNext() {
    delete this->next;
    this->next = nullptr;
  }

  ~StudentSpec() {
    this->removeNext();
  }
};
StudentSpec loadData() {

}

double getMathAverage(StudentSpec* student, double sum, int count) {
  if (student->next == nullptr) {
    return sum/count;
  }
  return getMathAverage(student->next, sum + student->math, count++);
}
int main() {
  StudentSpec *specList = new StudentSpec(12, 23, nullptr);
  int mathAve = getMathAverage(specList, 0, 1);
  return 0;
}