Matrix Inverse in C

#include<stdio.h>

int main(){

   

float A[10][10], ratio,a;

    int i, j, k;

  FILE *inputMatrixA=fopen("matrixA.txt","r");  //float data 3x3

  for(i=0;i<3;++i){

     for(j=0;j<3;++j){

         fscanf(inputMatrixA,"%f",&A[i][j]);

     }

  }

  fclose(inputMatrixA);

    for(i = 0; i < 3; i++){

        for(j = 3; j < 2*3; j++){

            if(i==(j-3))

                A[i][j] = 1.0;

            else

                A[i][j] = 0.0;

        }

    }

    for(i = 0; i < 3; i++){

        for(j = 0; j < 3; j++){

            if(i!=j){

                ratio = A[j][i]/A[i][i];

                for(k = 0; k < 2*3; k++){

                    A[j][k] -= ratio * A[i][k];

                }

            }

        }

    }

    for(i = 0; i < 3; i++){

        a = A[i][i];

        for(j = 0; j < 2*3; j++){

            A[i][j] /= a;

        }

    }

    printf("The inverse A is: \n");

    for(i = 0; i < 3; i++){

        for(j = 3; j < 2*3; j++){

            printf("%.4f", A[i][j]);

            printf("\t");

        }

        printf("\n");

    }

    return 0;

}