#include <stdio.h>
#include <math.h>
main()
{
    float b[5][6] = {
        { 2.3,6.5,4,-6,-8.3,15 },
        { 6.2,-8,-9.3,8,7,-6 },
        { 12.3,-14.7,9,4,3.6,-7 },
        { 3.6,8.6,-9.7,-12,13,5 },
        { 6.7,19,23,15,-8,17 },
    };
    int i, j;
    float d;
    for (i = 0; i < 5; i++) {
        for (j = 0; j < 6; j++)
            printf("[%i][%i]=%i\n", i, j, b[i][j]);
        printf("\n");
    }
    for (i = 0; i < 5; i++) {
        for (j = 0; j < 6; j++)
            b[i][j] /= b[i][2];
        
        printf("[%i][%i]=%i", i, j, b[i][j]);
        printf("\n");
    }
}