foo.cc: In function 'int main()':
foo.cc:9:2: error: expected ';' before 'float'
  float qian;
  ^~~~~
foo.cc:12:3: error: 'qian' was not declared in this scope
   qian=10;
   ^~~~
foo.cc:16:3: error: 'qian' was not declared in this scope
   qian=10+2.5*(a-3.0)+2.5*b; 
   ^~~~
foo.cc:20:3: error: 'qian' was not declared in this scope
   qian=(10+2.5*7)+3.75*(a-10.0)+3.75*b; 
   ^~~~
foo.cc:22:16: error: 'qian' was not declared in this scope
  printf("%.2f",qian);
                ^~~~

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