View Compilation Error

0_0_28482728_4586.cpp: In function 'int main()':
0_0_28482728_4586.cpp:27:17: error: 'a' was not declared in this scope
     case '/':if(a%b==0) printf("%d\n",a/b);else printf("%.2lf\n",(n*1.0)/(m*1.0));break;
                 ^
0_0_28482728_4586.cpp:27:19: error: 'b' was not declared in this scope
     case '/':if(a%b==0) printf("%d\n",a/b);else printf("%.2lf\n",(n*1.0)/(m*1.0));break;
                   ^