View Compilation Error

0_0_25773504_29359.cpp: In function 'int main()':
0_0_25773504_29359.cpp:12:3: error: 'ans' was not declared in this scope
   ans = a*pi+b*2;
   ^
0_0_25773504_29359.cpp:13:9: error: expected primary-expression before '=' token
   ans - = 0.0000005;
         ^