How do I correct "indefinite reference to 'function' in C?

Question

Here is a simple example of TAD, which shows the error.

file. h

#include <stdio.h>
#include <stdlib.h>

int teste();

file. c

#include "arquivo.h"

int teste()
{
    int a=5, b=10;

    return a+b;
}

main. c

#include "arquivo.h"

int main()
{
    int r = teste();

    printf("\n\n%d\n\n",r);

    return 0;
}

and when I compile the error appears below.

Answer 1

Include the arquivo.c in the compilation, without it the function is not compiled and does not exist, so it cannot be called.