A can have a piece of work done in 5 days, B can work three times faster than the A, C can work four times faster than A. How many days will they take to do the work together ?	Choose the correct choice from the following.
A) 3 days B) 8/9 days C) 3/2 days D) can't say E) none
A's 1 day work is 1/12   B's 1 day work is 3/12   3/2 days's 1 day work is 4/12   (A+B+3/2 days)'s 1 day work(1/12+3/12+4/12) is 2/3   so, they can finish the work in 3/2 days   ANSWER:3/2 days
<result>C</result>
A can have a piece of work done in 5 days, B can work three times faster than the A, C can work four times faster than A. How many days will they take to do the work together ?