PREP

40.
                5629-!-item-!-187;#058&004684

Six machines, each working at the same constant rate, together can complete a certain job in 12 days.  How many additional machines, each working at the same constant rate, will be needed to complete the job in 8 days?

(A) 2

(B) 3

(C) 4

(D) 6

(E) 8

答案是Ｂ