Help programs with functions "third year secondary school"

[=Dynamic=]

Hi, i'm new to this forum.
I attend the third year of secondary school.
today the teacher explained the functions but i didn't understand very well. kindly help me to carry out these programs in c. I use DevC++.

1- Calculate the sum and average of two vectors containing 5 integers. Compare the values ​​of the average viewing an appropriate message.
-Parameters of the average (sum, n_ele)
-Program with refunds

Thanks !

An example of my programs

#include <stdio.h>
#include <stdlib.h>
void Doppio (int n);
void Triplo (int n);
int main(void) {
    int n;
    printf("immetti n "); 
    scanf("%d",&n);
    Doppio(n);
    Triplo(n);
    system("pause");
    }
void Doppio (int n) {
     int Doppio;
     Doppio=n*2;
     printf("Il Doppio e' %d\n", Doppio); 
     return;
     }
void Triplo (int n) {
     int Triplo; 
     Triplo=n*3;
     printf("Il Triplo e' %d\n", Triplo);
     return;
}

[MK27]

Parameters of the average (sum, n_ele)

Okay, so:

int average (int sum, int n);

Where "sum" is the total of the values in the vector, and n is the number of values in the vector. The function returns an int. The definition is about 2-3 lines at most. I'm sure you've done enough math to figure out what they should be.

[=Dynamic=]

Thanks for the answer
This is the program, how do you think, it's ok?

#include <stdio.h>
#include <stdlib.h>
float media (float s, int n);
float media2 (float s2, int n);
main () {
     int n=5, i, v[n], v2[n], st;
     float s=0, s2=0;
     for(i=0; i<n; i++) {
     printf("Enter numbers first vector ");
     scanf("%d",&v[i]);
     }
     for(i=0; i<n; i++) {
     printf("Enter numbers second vector ");
     scanf("%d",&v2[i]);
     }
     for(i=0; i<n; i++) {
              s=s+v[i];
              }
     for(i=0; i<n; i++) {
              s2=s2+v2[i];
              }
     st=s+s2;
     printf("the sum of two vectors is %d\n",st);
     media(s,n);
     media2(s2,n);
     if(media>media2) {
     printf("The average of the first carrier is greater than the average of the second vector\n");
     }
     else {
     printf("The average of the second carrier is greater than the average of the first vector\n");
          }
     system("pause");
     }
     float media (float s, int n) {
         float media;
         media=s/5;
         printf("The average of first vector is %.2f\n",media);
         return media;
         }
     float media2 (float s2, int n) {
           float media2;
           media2=s2/5;
           printf("The average of second vector is %.2f\n",media2);
           return media2;
           }