A. (6 004+100)÷(1+9%)×9%=504(元) B. (6 004+100)×9%=549.36(元) C. 6 004÷(1+9%)×9%+100×9%=504.74(元) D. 6 004×9%+100÷(1+9%)×9%=548.62(元)