
A pretty easy read-calculate-write solution:
#includemain () { FILE *fin = fopen ("tax.in", "r"); FILE *fout = fopen ("tax.out", "w"); int cents, rate; fscanf (fin, "%d", ¢s); fscanf (fin, "%d", &rate); fprintf (fout, "%d\n", (int)(cents/100.0*rate+0.5)); exit (0); }