doubt about this code

referring to this code to calculate notes, but I have the second doubts, I know that the n is like a liminator (it's worth 2) but what does the aux and the n1 do?

#include<iostream>
#include<conio.h>
using namespace std;
struct alumno
{   char nombre[100];
    double t1, t2, ep, ef;
};
double promAula(alumno A[], int n, double aux,int n1){
    if (n == 0)
        return aux/ n1;
    else {
        double p = A[n - 1].t1*0.15 + A[n - 1].t2*0.15 +
            A[n - 1].ep*0.3 + A[n - 1].ef*0.4;
        aux += p;
        return promAula(A, n - 1, aux, n1);
    }
}
void main(){
alumno A[5]; 
int n = 2; 
double pa = 0;
    for (int i = 0; i < n; i++){
        cout << "Nombre: "; cin >> A[i].nombre;
        cout << "T1: "; cin >> A[i].t1;
        cout << "T2: "; cin >> A[i].t2;
        cout << "EP: "; cin >> A[i].ep;
        cout << "EF: "; cin >> A[i].ef;
    }
    cout << "Promedio Aula: " << promAula(A, n, pa, n);
    _getch();
}