View Compilation Error

0_0_21309839_19156.cpp: In function 'int main()':
0_0_21309839_19156.cpp:28:29: error: 'a' was not declared in this scope
             scanf("%lf%lf",&a[i],&b[i]);
                             ^
0_0_21309839_19156.cpp:28:35: error: 'b' was not declared in this scope
             scanf("%lf%lf",&a[i],&b[i]);
                                   ^
0_0_21309839_19156.cpp:40:31: error: 'mx' was not declared in this scope
          printf("%.8f %.8f\n",mx,m);
                               ^