A can have a piece of work done in 7 days, B can work five times faster than the A, C can work six times faster than A. How many days will they take to do the work together ? Choose the correct answer:
A) 3/2 days
B) 8/9 days
C) 4/3 days
D) can't say
E) none
3/2 days's 1 day work is 1/18   B's 1 day work is 5/18   C's 1 day work is 6/18   (3/2 days+B+C)'s 1 day work(1/18+5/18+6/18) is 2/3   so, they can finish the work in 3/2 days   3/2 daysNSWER:3/2 days
<result>A</result>
A can have a piece of work done in 7 days, B can work five times faster than the A, C can work six times faster than A. How many days will they take to do the work together ?