View Compilation Error

0_0_36705373_30921.cpp: In function 'double solve(int)':
0_0_36705373_30921.cpp:23:2: error: 'aa' was not declared in this scope
  aa=(xy-m*p1*p2)/(x2-m*p1*p1);
  ^
0_0_36705373_30921.cpp:24:2: error: 'bb' was not declared in this scope
  bb=p2-aa*p1;
  ^