foo.c: In function 'main':
foo.c:12:32: error: expected ';' before 'printf'
   12 |                 sum = (b - 1)*k
      |                                ^
      |                                ;
   13 |                 printf("%f", sum);
      |                 ~~~~~~          
foo.c:6:15: warning: variable 'sum' set but not used [-Wunused-but-set-variable]
    6 |         float sum = 0;
      |               ^~~

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