View Compilation Error

1_866_432_20159.cpp: In function 'int main()':
1_866_432_20159.cpp:27:3: error: 'double_t' was not declared in this scope
   double_t x;
   ^
1_866_432_20159.cpp:28:10: error: 'x' was not declared in this scope
   cin >> x;
          ^